CVE-2026-90832

Out-of-bounds read in Bluetooth Host periodic advertising report reassembly due to unvalidated report length

bt_hci_le_per_adv_report_common() in subsys/bluetooth/host/scan.c handles the HCI_LE_Periodic_Advertising_Report (and _v2) event. It verified that the fixed event header was present and that the controller-declared Data_Length fits the tailroom of the periodic-sync reassembly buffer, but never checked that the event actually carried as many data bytes as evt->length claims. Both reassembly paths — DATA_STATUS_PARTIAL, and DATA_STATUS_COMPLETE while a chain is already in progress — then called net_buf_simple_add_mem(&per_adv_sync->reassembly, buf->data, evt->length), copying up to 255 bytes starting past the end of the event's real payload. The Data_Length field originates in the HCI controller, so the flaw is reachable in host-only/split builds where the controller is a separate part reached over H4 UART, SPI, USB or an inter-core IPC transport: a malicious, compromised or buggy controller (or an attacker able to inject on that link) can send a report declaring a length larger than the event payload. The generic event dispatcher in subsys/bluetooth/host/hci_core.c only enforces a per-event minimum length and never cross-checks the subevent's internal length field, so nothing else catches it. Builds using Zephyr's own in-image controller are not affected, because the controller always emits a length matching the bytes it appends. Exploitation additionally requires CONFIG_BT_PER_ADV_SYNC with CONFIG_BT_PER_ADV_SYNC_BUF_SIZE > 0 (the option defaults to 0, which compiles the reassembly block out; LE Audio broadcast-sink and Public Broadcast Profile applications that reassemble fragmented periodic advertising data set it), and an established periodic advertising sync. The consequence is an out-of-bounds read of adjacent HCI RX-pool memory — including stale contents of previously received HCI events — which is copied into the reassembly buffer and then delivered to every registered bt_le_per_adv_sync_cb.recv listener as if it were received advertising data, so the disclosed memory becomes application-visible and may be forwarded off-device. The write side remains in bounds because the tailroom check uses the same length value, so there is no memory corruption; impact is limited to information disclosure and undefined behaviour on the over-read. The fix drops any report whose declared length exceeds the remaining event payload, matching the guard already present in the extended and legacy advertising report handlers.

CVSS 3.1 · 4.3 Medium EPSS < 1% KEV · Not listed

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CVE-2026-82391

Out-of-bounds write in Zephyr HTTP/2 server static-filesystem handler via corrupted receive-buffer length

The HTTP/2 front-end of the Zephyr HTTP server aliased connection receive state as a scratch output. In subsys/net/lib/http/http_server_http2.c, handle_http2_static_fs_resource() passed &client->data_len as the file_size out-parameter of http_server_find_file(). client->data_len is the count of unprocessed bytes remaining in the fixed-size per-connection receive buffer client->buffer[CONFIG_HTTP_SERVER_CLIENT_BUFFER_SIZE] (256 bytes by default), an invariant every frame handler and the socket receive path rely on. Serving any static file therefore replaced that bounded value with the file's on-disk size, and nothing resets it afterwards. The defect is reached by an unauthenticated HTTP/2 GET for any file under the web root, in applications that register a static-filesystem resource (HTTP_RESOURCE_TYPE_STATIC_FS) with CONFIG_FILE_SYSTEM=y; CONFIG_HTTP_SERVER_VERSION_2 is enabled by default and no TLS or credentials are required on this path. Once client->data_len exceeds the buffer size, the frame dispatch loop in subsys/net/lib/http/http_server_core.c keeps parsing past the end of the received data, and the peer controls the bytes at client->cursor, so it can choose which fabricated frame the state machine consumes next by appending bytes after its request. The inflated length defeats the only guards on the buffer. parse_http_frame_header() and the per-frame handlers read and skip up to a 24-bit frame length beyond the buffer (out-of-bounds read); the compaction memmove(client->buffer, client->cursor, client->data_len) at the end of request handling copies the file-size number of bytes into the 256-byte buffer, overflowing the rest of struct http_client_ctx — including the current_detail/current_stream pointers, the parser_settings function-pointer table and the inactivity_timer work handler — and the adjacent client contexts in static memory; and the subsequent zsock_recv(client->fd, client->buffer + client->data_len, sizeof(client->buffer) - client->data_len, 0) underflows its size argument, writing attacker-supplied data of attacker-chosen length out of bounds. The impact is remote memory corruption in the server's single address space: at minimum a crash or hang of the device, and plausibly control-data overwrite leading to code execution. The HTTP/1 and HTTP/3 static-filesystem handlers already used a local variable and are unaffected; the fix makes the HTTP/2 handler use a local size_t file_size as well.

CVSS 3.1 · 9.1 Critical EPSS < 1% KEV · Not listed

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CVE-2026-87042

Zephyr PTP: unvalidated Delay_Resp message interval lets an on-link peer wedge the PTP thread and flood the network

The IEEE 1588 (PTP) port implementation in subsys/net/lib/ptp/port.c adopted the logMessageInterval field of a received Delay_Resp message without any validation. port_delay_resp_msg_process() stored the raw wire value (a full-range int8_t) into port_ds.log_min_delay_req_interval, and that value is later used as a shift count by port_timer_set_timeout() when the Delay_Req timer is armed. Values below about -30 truncate the computed timeout to zero, and values with a magnitude of 64 or more perform an undefined shift of a uint64_t; the standards-defined "not applicable" encoding 0x7F fell into the latter case as well. PTP messages are received over unauthenticated link-local traffic (UDP multicast on 224.0.1.129, IPv6 multicast, or raw IEEE 802.3), and the handler accepts a Delay_Resp from any sender as long as the port is a time receiver using the end-to-end delay mechanism and the message echoes the port identity and a pending sequence id — both of which the victim itself broadcasts in its Delay_Req. Any node on the same link can therefore inject a single crafted Delay_Resp, or simply become the time transmitter and advertise the bogus interval. Once the delay timer is armed with a zero timeout, the cooperative PTP thread re-arms and retransmits a Delay_Req on every tick. Each transmission takes a buffer from the fixed CONFIG_PTP_MSG_POLL_SIZE message slab (default 10) and holds it on port->delay_req_list for three seconds, so the slab is emptied within milliseconds and ptp_msg_alloc() then blocks with K_FOREVER inside the only thread that frees those buffers — permanently stalling time synchronization until reboot. Where a transmit-timestamp callback on another thread keeps recycling buffers, the result is instead a sustained multicast Delay_Req flood and continuous CPU consumption. There is no memory corruption and no disclosure of data; the impact is availability of the PTP subsystem and of the local network segment. The fix rejects intervals outside a representable range and treats 0x7F as "not applicable" as required by IEEE 1588-2019 Table 42. The equivalent unchecked adoption of logMessageInterval from Sync messages in port_sync_msg_process(), a weaker variant of the same issue, is fixed by the companion change 334bf57f416f (#118150), which applies the same range check, ignores the field for unicast Sync messages and treats 0x7F as not applicable.

CVSS 3.1 · 6.5 Medium EPSS < 1% KEV · Not listed

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CVE-2026-77685

Bluetooth Classic RFCOMM: integer underflow in the MCC TEST command handler leads to out-of-bounds read disclosed to the peer and out-of-bounds write

The RFCOMM multiplexer control-channel handler in subsys/bluetooth/host/classic/rfcomm.c computed the echo length for a BT_RFCOMM_TEST command as buf->len - 1 and passed it to rfcomm_send_test(), whose length parameter is a uint8_t. A malformed but FCS-valid UIH frame on DLCI 0 can leave buf->len == 0 after rfcomm_handle_msg() pulls the two-byte MCC header, so buf->len - 1 underflows and narrows to 255. rfcomm_send_test() then copies 255 bytes out of a receive buffer that holds no remaining valid data, and appends them to an outgoing L2CAP PDU allocated with only CONFIG_BT_L2CAP_TX_MTU (253 by default for CONFIG_BT_CLASSIC) bytes of tailroom. The source read runs past the end of the ACL receive buffer into adjacent buffers of the same net_buf pool, and the destination copy overruns the transmit buffer by about eight bytes; net_buf_add_mem() performs no runtime bounds check in ordinary builds, where the underlying __ASSERT_NO_MSG() is compiled out. The trigger is a single five-byte RFCOMM frame on the multiplexer control channel, which is processed as soon as the L2CAP channel for PSM 3 is established — before any DLC exists and independent of RFCOMM session state. bt_rfcomm_init() registers that L2CAP server with .sec_level = BT_SECURITY_L1, which l2cap_br_conn_security() accepts without any link key from a peer that does not claim host Secure Simple Pairing support, so an unpaired BR/EDR device in radio range of a connectable target with CONFIG_BT_RFCOMM enabled (SPP, HFP, HSP, GOEP and similar profiles all enable it) can reach the defect. The resulting 255-byte TEST response is transmitted back to the attacker, disclosing roughly 255 bytes of adjacent stack/pool memory — including the contents of neighbouring receive buffers, which an attacker can prime with earlier packets — and the accompanying out-of-bounds write corrupts memory following the transmit buffer, which can crash the Bluetooth host. The request is trivially repeatable, so both the disclosure and the corruption can be driven at will. Two fixes are needed, and the first on its own does not close the out-of-bounds write. Fix 1 (0040ef781e1d, #115768) strips the FCS byte in rfcomm_recv() and echoes buf->len, rejecting anything over UINT8_MAX, which removes the underflow and the over-read. But rfcomm_make_uih_msg() still allocates the response with bt_l2cap_create_pdu() and never compares the requested length with the buffer's tailroom, so a well-formed TEST command carrying a pattern of about 248 bytes or more still builds a response (3-byte frame header, 2-byte message header, pattern, FCS) larger than the 253 bytes available. A pattern that long can only be received when the RFCOMM L2CAP receive MTU (CONFIG_BT_RFCOMM_L2CAP_MTU, which defaults to CONFIG_BT_BUF_ACL_RX_SIZE) exceeds CONFIG_BT_L2CAP_TX_MTU. The plain BR/EDR defaults (200 against 253) cannot reach it, but from v4.3.0 enabling CONFIG_BT_GOEP raises CONFIG_BT_BUF_ACL_RX_SIZE to 264 (265 from v4.4.0), so GOEP builds with only fix 1 applied still overrun the transmit buffer by up to eight bytes. This includes v4.3.2, the last v4.3 release, which carries fix 1 but will not receive fix 2. Fix 2 (214530895dd3, #118293) checks the tailroom on every RFCOMM PDU allocation and closes this residual write.

CVSS 3.1 · 8.3 High EPSS < 1% KEV · Not listed

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CVE-2026-90833

Signed offset bypasses bounds check in simulated EEPROM driver, allowing out-of-bounds kernel memory read and write from user mode

The simulated EEPROM driver validated access ranges in eeprom_range_is_valid() (drivers/eeprom/eeprom_simulator.c) with a single test, (offset + len) <= config->size. Because offset is a signed off_t and len an unsigned size_t of the same rank, the addition is evaluated in unsigned arithmetic: a negative offset combined with a compensating len wraps the sum back into the accepted range. eeprom_sim_read() and eeprom_sim_write() then memcpy() through the EEPROM(addr) macro, which is plain pointer arithmetic on the driver's static mock_eeprom array, so the copy addresses memory located before that array. eeprom_read() and eeprom_write() are __syscall entry points, and their verification handlers in drivers/eeprom/eeprom_handlers.c check only the device object and the caller's own data buffer (K_SYSCALL_MEMORY_READ/K_SYSCALL_MEMORY_WRITE) — the offset argument is passed to the driver unvalidated. With CONFIG_USERSPACE=y, a CONFIG_EEPROM_SIMULATOR device instance, and the device object granted to a user thread (the usage the in-tree tests/drivers/eeprom/api suite exercises from ZTEST_USER threads), an unprivileged thread could supply a negative offset and have the kernel perform the copy on its behalf. The result is an out-of-bounds read of kernel .bss returned into the caller's buffer and, via the write path, an out-of-bounds write of caller-supplied bytes over kernel memory preceding mock_eeprom. Both the start address and the length of the affected span are attacker-selected, so the primitive is sufficient to corrupt adjacent kernel state and escape the user-mode sandbox. Exposure is limited to builds that instantiate the simulated EEPROM (status = "okay" by default on qemu_x86 and native_sim, otherwise added by a devicetree overlay) together with userspace isolation. The fix rejects negative offsets and performs the remaining bound check without overflow.

CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed

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CVE-2026-90834

UART wide-data syscall verifiers check the 8-bit driver op, allowing a user-mode thread to trigger a NULL function-pointer call in kernel mode

The user-mode syscall verifiers for the 16-bit ("wide data") UART API in drivers/serial/uart_handlers.c validated the wrong driver operation. z_vrfy_uart_poll_out_u16(), z_vrfy_uart_tx_u16() and z_vrfy_uart_rx_enable_u16() each ran K_SYSCALL_DRIVER_UART() against the 8-bit op (poll_out, tx, rx_enable) rather than the 16-bit op that the corresponding implementation dereferences (poll_out_u16, tx_u16, rx_enable_u16). z_impl_uart_poll_out_u16(), z_impl_uart_tx_u16() and z_impl_uart_rx_enable_u16() in include/zephyr/drivers/uart/uart_internal.h call their op unconditionally, with no NULL guard of their own, because the verifier is supposed to have established that the op exists. CONFIG_UART_WIDE_DATA is an application-selectable option that no driver selects, and only a handful of the serial drivers in the tree implement any _u16 operation; every other driver leaves those struct uart_driver_api members NULL while still providing the 8-bit ops the old check inspected. In a build with CONFIG_USERSPACE and CONFIG_UART_WIDE_DATA (plus CONFIG_UART_ASYNC_API for the uart_tx_u16() and uart_rx_enable_u16() variants), an unprivileged user-mode thread that legitimately holds access to such a UART device object can invoke the _u16 syscall: the object, permission and op checks all pass, and the kernel-side implementation then performs an indirect call through a NULL function pointer while running at supervisor privilege. The result is a CPU exception taken in kernel context instead of the intended K_OOPS or -ENOSYS return. With the default k_sys_fatal_error_handler() this halts the system (or warm-reboots it under CONFIG_RESET_ON_FATAL_ERROR), so a thread confined by the userspace sandbox can deny service to the whole device — a capability the user-mode privilege boundary is specifically meant to withhold. The call target is a fixed NULL, so there is no attacker-controlled code execution and no memory disclosure; the separate K_SYSCALL_MEMORY_ARRAY_READ()/K_SYSCALL_MEMORY_ARRAY_WRITE() bounds checks on the caller's buffer were and remain correct. The fix points each verifier at the matching _u16 op, using a plain K_SYSCALL_OBJ() object check where the op does not exist or where the implementation already tests it for NULL.

CVSS 3.1 · 5.5 Medium EPSS < 1% KEV · Not listed

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CVE-2026-91007

Arbitrary supervisor-mode function pointer injection via charger_set_prop() syscall in the charger driver API

The user-mode syscall verifiers for the charger driver API in drivers/charger/charger_handlers.c did not inspect the prop argument before copying union charger_propval across the user/kernel boundary. Two members of that union are function pointers — status_notification (CHARGER_PROP_STATUS_NOTIFICATION) and online_notification (CHARGER_PROP_ONLINE_NOTIFICATION), declared in include/zephyr/drivers/charger.h — and z_vrfy_charger_set_prop() forwarded the caller-supplied union verbatim to the driver's set_property callback for any property. z_vrfy_charger_get_prop() had the mirror defect and copied the stored kernel callback address back out to user memory. With CONFIG_USERSPACE enabled, any user-mode thread that has been granted a charger device object could call charger_set_prop() with CHARGER_PROP_STATUS_NOTIFICATION or CHARGER_PROP_ONLINE_NOTIFICATION and an arbitrary pointer value. Drivers that implement these properties — drivers/charger/charger_max20335.c, drivers/charger/charger_pf1550.c and drivers/charger/charger_bq2518x.c — store the pointer in device data and later invoke it from their interrupt work handlers, which run in supervisor mode, on any charger state change such as a cable plug/unplug. The result is a control-flow hijack at kernel privilege from an unprivileged thread, defeating the isolation that CONFIG_USERSPACE is meant to provide; the read path additionally disclosed a kernel code address to user mode, and clearing a notifier installed by a supervisor thread let user mode suppress charger notifications. Supervisor-mode callers of charger_set_prop()/charger_get_prop() are unaffected. The fix makes both verifiers reject the two notifier properties outright — including when the supplied callback is NULL, since the notifiers are device state — and adds a BUILD_ASSERT on CHARGER_PROP_COMMON_COUNT so that new properties force a re-review of the union's user-mode safety.

CVSS 3.1 · 7.8 High EPSS n/a KEV · Not listed

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CVE-2026-19809

Kernel stack information disclosure in the charger_get_prop() system call handler

The user-mode system call verifier z_vrfy_charger_get_prop() in drivers/charger/charger_handlers.c declares an uninitialized union charger_propval k_val on the kernel (privileged) stack, passes it to the charger driver back end via z_impl_charger_get_prop(), and then copies the full sizeof(union charger_propval) back into the calling user thread's buffer with k_usermode_to_copy(). That discloses kernel stack contents on two paths: On error. The copy-out ignores the driver's return code. In-tree back ends return an error without writing through the value pointer for properties they do not implement: charger_gpio_get_prop() returns -ENOTSUP unconditionally, and bq24190_get_prop() has a default: return -ENOTSUP; arm that never touches val. The whole union is then stack residue. On success. A back end writes only the one union member the requested property selects (for example sbs_charger.c writes the one-byte val->present for CHARGER_PROP_PRESENT and returns 0), yet the handler still copies the whole union, so every byte beyond that member is uninitialized. The handler is compiled only when CONFIG_USERSPACE=y and is reachable by any user-mode thread that has been granted access to a charger device object. K_SYSCALL_DRIVER_CHARGER() validates only the device object and its API pointer, not the property identifier, so an unprivileged thread can choose prop freely: an unimplemented property forces the error path, a narrow one the success path, and the call can be repeated at will. Each call discloses up to the size of the union (12 bytes on a 32-bit target, 16 bytes on 64-bit targets where the function-pointer members widen it) of supervisor-stack memory. The bytes are residue of earlier kernel-side frames on the thread's privileged stack and can contain kernel object addresses and saved return addresses, which an unprivileged thread cannot otherwise observe and which help defeat address-layout assumptions when exploiting a separate memory-safety defect. There is no integrity or availability impact. Two commits fix it, and both are needed. 5054384e983c skips the copy-out when the back end reports an error. c31cac727d02 zeroes the union before the driver call, so the bytes copied out on success are driver-written data or zeros. A tree carrying only the first still leaks on every successful call.

CVSS 3.1 · 3.3 Low EPSS n/a KEV · Not listed

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CVE-2026-87045

NULL pointer dereference in the Zephyr HTTP/2 server when a header block is completed by a CONTINUATION frame

The HTTP/2 server in subsys/net/lib/http/http_server_http2.c clears the connection's stream binding at the start of every frame. handle_http_frame_header() executed client->current_stream = NULL unconditionally, but a CONTINUATION frame does not open a new stream and enter_http_frame_continuation_state() never re-bound one, so the rest of the header block was processed with client->current_stream unset. Two paths then write through the NULL pointer. A request for an unregistered resource, or a method the matched resource does not support, is answered by send_http2_404() or send_http2_405(), and both call send_headers_frame(), which unconditionally sets client->current_stream->headers_sent = true. A POST, PUT or PATCH to a registered dynamic resource reaches handle_http2_dynamic_resource(), which unlike its siblings (handle_http2_static_resource(), dynamic_get_del_opts_req_v2(), dynamic_post_put_req_v2()) had no client->current_stream == NULL guard, and stores through the pointer with client->current_stream->current_detail = dynamic_detail. Any peer that can reach the server can trigger this without authentication or prior state. A single stray CONTINUATION frame with END_HEADERS set, sent right after the client preface and requesting any unregistered path, is enough, because nothing rejected a CONTINUATION that no HEADERS frame had opened. A legitimate split header block (a HEADERS frame with END_HEADERS clear whose payload ends on a header-field boundary, then a CONTINUATION with END_HEADERS set) reaches the same state. The in-tree test test_http2_post_headers_with_continuation() did not catch this because it splits the header block mid field, which takes the handle_incomplete_http_header() shortcut that keeps the stream bound. The result is a write to a fixed low address (a small offset into struct http2_stream_ctx), which faults on mainstream targets (flash/vector-table region on Cortex-M, or a trap under MPU/MMU null-pointer detection), and the default fatal-error handler halts the system. Impact is an unauthenticated, remotely triggerable denial of service against any device running the HTTP/2 server: the 404 path needs no particular resource to be registered, and HTTP/2 is built into CONFIG_HTTP_SERVER with cleartext h2c accepted, so TLS does not prevent it. Neither the target address nor the written value is attacker-controlled, so there is no confidentiality or integrity impact. Applications built without CONFIG_HTTP_SERVER are not affected.

CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed

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CVE-2026-90586

Xtensa MMU userspace: uninitialized thread page-table pointer leads to out-of-bounds supervisor-mode writes

The Xtensa MMU userspace port never initialized the per-thread page-table pointer thread->arch.ptables during thread setup, while arch_mem_domain_thread_add() in arch/xtensa/core/ptables.c uses a non-NULL value of that field as its "this thread is migrating from another memory domain" predicate. For a thread whose struct k_thread backing memory is not zeroed, the field holds stale data and the kernel takes the migration branch, passing that stale value to reset_region() as the base of a level-1 page table. The equivalent field on x86 is explicitly cleared in z_x86_userspace_prepare_thread() for exactly this reason; the Xtensa port adopted the predicate without the initialization. The condition is reachable from an unprivileged user-mode thread on a build with CONFIG_XTENSA_MMU, CONFIG_USERSPACE and dynamically allocated kernel objects. k_object_alloc(K_OBJ_THREAD) is a system call and allocates the thread object from the caller's resource pool without zeroing it, and the k_thread_create() verifier accepts such an object while forcing the K_USER option, so the migration branch is taken whenever the recycled heap bytes at that offset are non-zero. Because a user thread can also allocate, fill and free other kernel objects from the same heap, the stale bytes are groomable rather than merely random. Walking the bogus table in region_map_update() performs an unguarded index into l2_page_tables_counter[], may copy from and write through the attacker-influenceable level-1 base in dup_l2_table_if_needed(), and finally writes a page-table entry through a second pointer read out of that memory — once per page of the new thread's stack. The result is out-of-bounds reads and writes executed in supervisor mode, ranging from an immediate kernel panic (observed as Xtensa EXCAUSE 13 on Intel ADSP DSP firmware with user threads) to corruption of kernel memory and escape from the user-mode sandbox.

CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed

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CVE-2026-90587

NULL pointer dereference in the Zephyr USB host stack when a device reports zero configurations

usbh_device_init() in subsys/usb/host/usbh_device.c rejects a device whose device descriptor advertises bNumConfigurations == 0, but it only logs the error and jumps to the cleanup label without setting the return code. At that point the local err is still 0 from the preceding successful descriptor read, so the function returns success while having skipped usbh_device_set_configuration() — the only place udev->cfg_desc is allocated. The device structure is zero-initialised by usbh_device_alloc(), so udev->cfg_desc remains NULL. usbh_device_connect() treats the zero return as a successful enumeration and calls usbh_class_probe_device(), which starts its descriptor walk from udev->cfg_desc. usbh_desc_get_next_function() passes that NULL pointer to usbh_desc_is_valid(), whose only guard compares the caller-supplied size, so head->bLength is read through a NULL pointer. The condition is triggered entirely by the attached peripheral: attaching a USB device (or any USB gadget emulating one) that reports bNumConfigurations = 0 reaches the defect directly from the UHC_EVT_DEV_CONNECTED_FS/_HS event handler in subsys/usb/host/usbh_core.c, with no authentication and no user interaction beyond the physical attachment. On targets where page zero is unmapped or CONFIG_NULL_POINTER_EXCEPTION_DETECTION is enabled this raises a fatal exception in the USB host thread, denying service to the host. Where address zero is readable, the descriptor walker instead parses low memory as a descriptor chain and can dispatch a class probe() with attacker-influenced values, causing further out-of-bounds reads through the still-NULL udev->cfg_desc in usbh_desc_get_iface(). No attacker-controlled write was identified, so the impact is availability plus a bounded out-of-bounds read. Note that CONFIG_USB_HOST_STACK is marked experimental.

CVSS 3.1 · 4.6 Medium EPSS < 1% KEV · Not listed

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CVE-2026-90588

Out-of-bounds read in Zephyr HTTP client debug logging of response header fields

The HTTP client's debug helper print_header_field() in subsys/net/lib/http/http_client.c formatted an http_parser data-callback slice with a %s conversion: snprintk(output, len + 1, "%s", str). The parser hands its callbacks a pointer and a length into the caller's receive buffer, and those bytes are not NUL terminated. The size argument of snprintk() bounds only the destination, while the %s conversion measures the source first — lib/os/cbprintf_complete.c uses strlen() when no precision is given, and lib/os/cbprintf_nano.c uses strlen() unconditionally — so the read walks past the end of the header field and past the end of the receive buffer until it finds a zero byte. The slice reaches the helper from on_url(), on_header_field() and on_header_value(), which the parser invokes on bytes that http_wait_data() read straight off the socket into the application-supplied recv_buf. A malicious or compromised HTTP server, or an attacker able to answer a plaintext request, therefore controls both the header field and the bytes that follow it in the buffer, and can guarantee that no zero byte appears before the buffer ends, forcing the over-read. The in-tree tests/net/lib/http_client suite reproduces the over-read under CONFIG_ASAN=y on an ordinary GET. The impact is bounded. The whole helper body is compiled only when the HTTP client log module is explicitly set to Debug (CONFIG_NET_HTTP_LOG_LEVEL_DBG=y, which the global CONFIG_LOG_DEFAULT_LEVEL does not set), so default builds are unaffected. No out-of-bounds write occurs and none of the over-read bytes are emitted into the log, so there is no information disclosure; the consequence is an out-of-bounds read that can fault and panic the device where the buffer abuts an unmapped or MPU/MMU-protected region. The fix copies exactly the len bytes the parser offered with memcpy() and terminates them, instead of relying on a %s conversion (a %.*s precision would not have sufficed, since cbprintf_nano.c measures the source in full before applying it).

CVSS 3.1 · 3.7 Low EPSS < 1% KEV · Not listed

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CVE-2026-90589

Memory-mapped thread stack is never unmapped when a thread is aborted by another thread, exhausting kernel virtual address space

When CONFIG_THREAD_STACK_MEM_MAPPED is enabled, each thread stack is mapped into the kernel virtual address space with a guard page on either side, and the mapping is released during abort cleanup. k_thread_abort_cleanup() in kernel/thread.c has two paths: a deferred one for self-abort, which stashes the mapping in thread_cleanup_stack_addr/thread_cleanup_stack_sz, and an immediate one for a thread aborted by some other thread. The immediate path called do_thread_cleanup(), which ignored its thread argument and only ever unmapped the stashed address — a value populated exclusively by the self-abort path. The mapped stack of a thread aborted by another thread was therefore never unmapped. Every k_thread_abort() of a non-current thread leaks the thread's stack region plus its two guard pages from the kernel virtual address space. Threads that end by returning from their entry function take the working self-abort path, so the leak is specific to explicit cancellation — k_thread_abort(), pthread_cancel(), osThreadTerminate(), or the kernel thread kill shell command. Both k_thread_create() and k_thread_abort() are system calls, so with CONFIG_USERSPACE an unprivileged user-mode thread that has been granted a thread object and a user-capable stack object can drive the leak from user mode, consuming a kernel-side resource it cannot otherwise touch. With CONFIG_KERNEL_VM_SIZE defaulting to 8 MB, a few hundred create/abort cycles exhaust the runtime mapping region. k_mem_map_phys_guard() then returns NULL, and map_thread_stack() guards that only with __ASSERT_NO_MSG(), which is compiled out of production builds; thread creation proceeds to write through a NULL-derived stack base and faults in kernel mode. The impact is a persistent denial of service — a kernel fatal error requiring a reboot — with no memory disclosure or corruption, and it is limited to configurations where memory-mapped thread stacks are enabled (x86 targets with X86_MMU and demand paging disabled, where the option is implied by default).

CVSS 3.1 · 5.5 Medium EPSS < 1% KEV · Not listed

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CVE-2026-90585

Renesas RA SCI UART driver: unacknowledged receive-error interrupt causes a permanent interrupt storm and CPU lockup

The Renesas RA SCI UART driver's receive-error ISR, uart_ra_sci_eri_isr() in drivers/serial/uart_renesas_ra_sci.c, acknowledged the error condition only when a Zephyr interrupt-driven callback had already been registered. With CONFIG_UART_INTERRUPT_DRIVEN=y and CONFIG_UART_ASYNC_API=n, if data->user_cb is NULL the ISR body is empty: the SCI error flags (SSR.ORER, SSR.FER, SSR.PER) are left set and the ICU event flag R_ICU->IELSR_b[eri_irq].IR is never cleared, so the interrupt re-pends immediately and the ISR is re-entered without end. The error interrupt is masked at boot by uart_ra_sci_init(), but FSP's R_SCI_UART_Open() unconditionally re-enables it, and uart_ra_sci_configure() - the back end of the public uart_configure() API, enabled by default via CONFIG_UART_USE_RUNTIME_CONFIGURE - performs a Close()/Open() pair without re-masking it. Any runtime uart_configure() therefore leaves the error interrupt live regardless of whether a callback has been set, as does calling uart_irq_err_enable() on its own. An instance used with the polling API, or the window between uart_configure() and uart_irq_callback_user_data_set(), thus runs with the error interrupt unmasked and no callback registered. The trigger is an ordinary receive line error - overrun, framing, parity, or a break condition - which is fully determined by the device attached to the serial link. A peer able to assert a break or transmit at a mismatched baud rate produces such an error at will, so a single frame is enough to enter the state. The impact is availability only: the CPU is captured in the re-entering ISR and never returns to thread context, hanging the entire system until an external reset or hardware watchdog fires. There is no memory corruption or information disclosure. Builds using the asynchronous UART API are unaffected, because the fall-through to FSP's sci_uart_eri_isr() clears both the error flags and the pending IRQ.

CVSS 3.1 · 4.6 Medium EPSS < 1% KEV · Not listed

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CVE-2026-90590

Permanent loss of transmit capability in the NXP ENET QoS Ethernet driver after an Ethernet link drop

The NXP ENET QoS Ethernet driver in drivers/ethernet/eth_nxp_enet_qos serialises transmission with a binary semaphore, data->tx.tx_sem, taken in eth_nxp_enet_qos_tx() and returned only by the transmit-completion interrupt handler tx_dma_done(). A frame that has been handed to the transmit DMA when the Ethernet link goes down is never written back, so that completion interrupt never arrives. The PHY callback eth_nxp_enet_qos_phy_cb() reacts to carrier loss only by calling net_eth_carrier_set(); it does not stop the DMA, take the descriptors back or release the outstanding frame, and no timeout exists to do so. The trigger is a link-down/link-up transition that lands while a frame is under the transmit DMA. It can be produced by anyone who controls the link partner or the cable — for example by administratively downing and restoring the attached switch port, or by restarting auto-negotiation from a peer device — and can be made reliable by generating traffic that keeps the device transmitting and repeating the transition. No credentials or user interaction are required, and the trigger is at the link layer rather than over IP. Because the semaphore is never given back, every subsequent call to eth_nxp_enet_qos_tx() fails with -EBUSY for the remaining life of the boot; restoring the link does not recover the interface, since the link-up path only rewrites MAC_CONFIGURATION. The affected interface continues to receive but can no longer transmit anything — no ARP replies, no TCP acknowledgements, no DHCP renewals — until the device is reset. The net_pkt and the net_buf fragments of the abandoned frame are likewise never unreferenced and never return to their pools. The security-relevant property is persistence: a momentary link flap leaves the interface permanently unable to send, so the denial of service outlasts the attacker's access to the link. There is no confidentiality or integrity impact. The fix adds a claim/release pair around the outstanding packet so that completion and abandonment are mutually exclusive, aborts an outstanding frame from the PHY callback on carrier loss (stopping the DMA, flushing the MTL transmit queue and reinitialising the descriptor ring), and arms a transmit watchdog, CONFIG_ETH_NXP_ENET_QOS_TX_TIMEOUT_MS, so that any non-completing DMA — not only a carrier loss — reclaims the transmit slot and the packet.

CVSS 3.1 · 6.5 Medium EPSS < 1% KEV · Not listed

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CVE-2026-90591

NXP ENET-QOS Ethernet driver re-arms RX descriptors with a clobbered DMA buffer address on packet drop

The NXP ENET-QOS Ethernet driver's receive work handler eth_nxp_enet_qos_rx() in drivers/ethernet/eth_nxp_enet_qos hands each processed descriptor back to the DMA by writing desc->read.control = rx_desc_refresh_flags, which sets OWN_FLAG and BUF1_ADDR_VALID_FLAG. RDES0 of a receive descriptor is the DMA buffer address in read format, but the hardware write-back aliases that word with the VLAN tag fields (or, for a context descriptor, the timestamp low word), so it is destroyed on every completion. The success path rewrites desc->read.buf1_addr before re-arming; the four drop paths — errored or non-first descriptor, net_pkt_rx_alloc() failure, invalid descriptor length, and net_pkt_get_frag() failure — did not, re-arming the ring slot with the write-back residue as its DMA target address. The drop paths are driven entirely by received traffic and need no privilege or special configuration. With the defaults for this driver (CONFIG_NET_BUF_DATA_SIZE of 128 and 16 receive descriptors) a single full-size frame consumes twelve ring slots and twelve K_NO_WAIT fragment allocations, so a short burst of frames sent to the device exhausts the receive pools and reaches the allocation-failure paths; a frame with a receive error, or any frame whose first descriptor was already dropped, reaches the non-first-descriptor path. Once a slot has been poisoned, the DMA writes the next frame received in that slot to an address derived from the frame's VLAN tag fields rather than to a receive buffer. On the supported MCX SoCs that address falls in flash or reserved space, so the transfer raises a fatal bus error that the driver only logs — there is no reset or recovery path — and reception stops permanently until the device is rebooted; where the write is silently discarded instead, the untouched buffer is later handed to the network stack with a length, delivering stale buffer contents as if they were a received frame. A single triggering event is enough to make the condition persistent, so an attacker able to send traffic to the device can permanently disable its network interface.

CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed

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CVE-2026-87044

Memory leak in the Mbed TLS crypto shim on failed cipher/AEAD operations leads to remotely triggered crypto denial of service

The Mbed TLS crypto shim driver in drivers/crypto/crypto_mbedtls_shim.c drives PSA multipart cipher and AEAD operations. In mbedtls_cbc() and mbedtls_aead(), every error path after a successful psa_cipher_encrypt_setup() / psa_aead_decrypt_setup() returned directly without calling psa_cipher_abort() / psa_aead_abort(). Because the abort is the only thing that reaches mbedtls_cipher_free(), each failed operation permanently leaked the heap-allocated mbedtls_aes_context (roughly 288 bytes) that setup had allocated from Mbed TLS's fixed static heap (_mbedtls_heap[CONFIG_MBEDTLS_HEAP_SIZE], default 512 bytes). With CONFIG_PSA_CRYPTO_PROVIDER_TFM the leaked object is instead a finite secure-partition multipart-operation slot. The failure is chosen by an unauthenticated attacker. With CONFIG_NET_L2_IEEE802154_SECURITY backed by this driver, ieee802154_decrypt_auth() in subsys/net/l2/ieee802154/ieee802154_security.c invokes cipher_ccm_op() on every received secured frame, with no authentication ahead of the MIC check. A device in radio range can transmit a stream of syntactically valid 802.15.4 frames carrying a bogus MIC; each one makes psa_aead_verify() fail and leaks a block. The CBC path is reachable the same way through the OSDP secure channel, where CONFIG_OSDP_SC_ENABLED selects this shim and osdp_encrypt() / osdp_decrypt() leave out_buf_max unset, so every operation fails inside psa_cipher_update(). Exhausting the Mbed TLS heap — which the default configuration reaches after a couple of failed operations, and any realistic configuration reaches in well under a second of frames — makes all subsequent mbedtls_calloc() calls fail. Every later cryptographic operation in the image then fails permanently, including link-layer security and any TLS/DTLS sharing the same heap, until the device is rebooted. There is no memory corruption or information disclosure: frames with an invalid MIC are still rejected, so the impact is limited to availability. The fix routes all post-setup failures in mbedtls_cbc() and mbedtls_aead() through a common error: label that calls the matching PSA abort before returning. Setup failures need no change, since the PSA core aborts the operation itself when setup fails.

CVSS 3.1 · 6.5 Medium EPSS < 1% KEV · Not listed

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CVE-2026-87043

sys_rand_get() silently returns an unwritten buffer when the entropy device is not ready

The entropy-device random number generator in subsys/random/random_entropy_device.c returned early with -ENODEV from rand_get() as soon as device_is_ready() failed, before reaching the non-cryptographic system-timer fallback further down the same function. Because z_impl_sys_rand_get() returns void and discards that error — and the public sys_rand_get() syscall is itself declared void, so it cannot report failure — the caller's output buffer was left untouched and its previous contents were handed back as random data. The thin wrappers make this a plain uninitialized read: sys_rand32_get() declares uint32_t ret;, calls sys_rand_get(&ret, sizeof(ret)) and returns ret. The "not ready" state is a normal runtime condition rather than a fault. Entropy drivers initialise at PRE_KERNEL_1 with CONFIG_ENTROPY_INIT_PRIORITY (default 50), so any earlier initialiser — kernel objects run at priority 30 — observes an unready device; the sibling generator subsys/random/random_xoshiro128.c and z_early_rand_get() in kernel/init.c both already carried an explicit timer fallback for exactly this case. The state is also permanent for the boot when an entropy driver's init hook fails, which several in-tree drivers can do on real hardware (entropy_stm32 on an RNG clock configuration error, entropy_psa_crypto when psa_crypto_init() fails, entropy_nrf_cracen, entropy_esp32, entropy_virtio). When this occurs, every non-cryptographic random value in the system is either a constant or stale memory. coap_next_token() in subsys/net/lib/coap/coap.c fills a static buffer, so every CoAP token becomes the same .bss constant; tcp_init_isn() in subsys/net/ip/tcp.c returns an uninitialized stack word as the TCP initial sequence number; DHCPv4/DHCPv6 transaction IDs, WebSocket masking keys and RTP SSRCs are similarly degraded, and arch/arm64/core/pac.c derives per-thread Pointer Authentication keys from the same source. Where the bytes are transmitted directly — SSH packet padding, the netmidi2 session nonce, a DTLS connection ID on builds without CONFIG_CSPRNG_ENABLED — stale caller stack or heap contents are disclosed on the wire. The fix initialises ret to -ENODEV and only calls entropy_get_entropy() when the device is ready, so the not-ready case now falls through to the timer fallback and the buffer is always written. The cryptographically secure path is unchanged: sys_csrand_get() still propagates the error to the caller and never silently degrades. An attacker cannot induce the unready state, but can observe and exploit the resulting non-random values remotely on an affected device.

CVSS 3.1 · 4.8 Medium EPSS < 1% KEV · Not listed

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CVE-2026-87041

Inverted memory-permission check in the RTIO syscall verifier allows a user-mode thread to read and write arbitrary kernel memory

The RTIO submission-queue verifier rtio_vrfy_sqe() in subsys/rtio/rtio_syscalls.c (subsys/rtio/rtio_handlers.c before v4.3.0) accumulated the results of K_SYSCALL_MEMORY() into its valid_sqe flag with &=. That macro returns nonzero on failure (it is built on K_SYSCALL_VERIFY_MSG(), which yields !(expr)), so every buffer permission check contributed the opposite of its result. A submission whose tx.buf, rx.buf or txrx.tx_buf/txrx.rx_buf pointer was not accessible to the calling thread was accepted, while a legitimate, thread-owned buffer caused the calling thread to be killed with a kernel oops. The verifier runs on behalf of the rtio_sqe_copy_in_get_handles() system call (also reached through the inline rtio_sqe_copy_in() wrapper), so it is driven directly by untrusted user-mode input on any image built with CONFIG_USERSPACE. A user thread that has been granted an RTIO context and an rtio_iodev object — the intended usage of RTIO userspace support, established via rtio_access_grant() — can submit an SQE whose buffer pointer and length name arbitrary kernel memory; the object check on sqe->iodev is unaffected and still passes, and the crafted SQE is forwarded to the bus driver unchanged. Downstream consumers dereference the pointer with supervisor privilege. The generic I2C and I3C RTIO fallback handlers (drivers/i2c/i2c_rtio_default.c, drivers/i3c/i3c_rtio_default.c) copy sqe.rx.buf/sqe.tx.buf into struct i2c_msg and call i2c_transfer(), and the vendor SPI/I2C RTIO drivers behave equivalently. An RTIO_OP_RX submission therefore has peripheral data written into kernel memory of the attacker's choosing (arbitrary kernel write), an RTIO_OP_TX submission clocks kernel memory out over the bus (kernel memory disclosure), and a pointer to unmapped memory faults the kernel. This is a full escape from the user-mode isolation boundary that CONFIG_USERSPACE exists to enforce. The defect was masked for years because the in-tree user-mode RTIO tests only exercise RTIO_OP_NOP and mempool-backed reads, neither of which reaches the affected checks. The fix negates each K_SYSCALL_MEMORY() result and additionally validates the TXRX transmit buffer read-only, matching the SPI, I2C and I3C handlers.

CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed

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CVE-2026-87040

Bluetooth LE Controller accepts received PDUs whose length field exceeds the configured maximum receive length, causing out-of-bounds read and write

The nRF link-layer receive paths of the open-source Bluetooth LE Controller did not validate the on-air LENGTH field of a received PDU against the maximum receive length that was used to program the radio. isr_rx_pdu() in subsys/bluetooth/controller/ll_sw/nordic/lll/lll_conn.c enqueued any non-empty data PDU after only the sequence-number and (for encrypted links) MIC checks, and the corresponding isr_rx() handlers in lll_central_iso.c, lll_peripheral_iso.c, lll_sync_iso.c and lll_scan_aux.c did the same for ISO and extended-advertising PDUs. The nRF radio stores the received header verbatim and truncates only the payload at PCNF1.MAXLEN, so a frame declaring more octets than were configured leaves a node buffer whose len field describes more data than the buffer holds. An attacker within radio range that can emit a hand-crafted link-layer PDU — for a connection, any peer that establishes an unencrypted LE connection to a connectable advertiser; for CONFIG_BT_CTLR_SYNC_ISO, any broadcaster the device is synchronised to — can set the length byte up to 255 while the controller has programmed a much smaller maximum (lll->dle.eff.max_rx_octets, which is 27 until a Data Length Update, or the negotiated cis_lll->rx.max_pdu). No pairing, authentication or user interaction is required. On encrypted links the CCM MIC check normally rejects such a frame first, so the exposure is on unencrypted traffic, which is why the added check is placed after decryption. The unchecked length reaches hci_acl_encode() in subsys/bluetooth/controller/hci/hci.c, which performs net_buf_add(buf, pdu_data->len) followed by a memcpy() of that many bytes out of the node_rx pool element. Because CONFIG_BT_CTLR_DATA_LENGTH_MAX and CONFIG_BT_BUF_ACL_RX_SIZE both default to 27, this is an out-of-bounds read of up to roughly 228 bytes past the received PDU and a corresponding out-of-bounds write past the HCI ACL buffer into neighbouring buffers of the same pool; the tailroom test in net_buf_simple_add() is only enforced when CONFIG_NET_BUF_HARDENING (or CONFIG_ASSERT) is enabled. On the ISO paths the same unchecked length makes isoal_rx_append_to_sdu() read past the ISO node buffer and emit adjacent controller RAM to the host as ISO data. The practical result is remote memory corruption and controller crashes, plus disclosure of controller memory into the host data path. The fix rejects any received PDU whose length exceeds the value that was used to configure the radio reception. Note that lll_sync.c (periodic advertising sync reception) was not changed and still enqueues received PDUs without an equivalent bound.

CVSS 3.1 · 8.3 High EPSS < 1% KEV · Not listed

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