CVE-2026-98294

Bluetooth: hci_qca: Do not write to the serial port after it is closed

Published Oct 6, 2026 CVSS 3.1 · 5.5 Medium EPSS < 1% KEV · Not listed
Description
In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: hci_qca: Do not write to the serial port after it is closed

hci_uart_close() closes the serdev port if HCI_QUIRK_NON_PERSISTENT_SETUP
is set (for example, for the WCN399x family). A failed hci_dev_open_sync()
following a successful qca_setup() calls hdev->close() but not
hdev->shutdown(), so the port is closed while power->vregs_on is left true.
qca_serdev_remove() then passes its power->vregs_on test and calls
qca_power_off(), which writes to the closed port unconditionally.

Seen on a WCN3988 by unbinding the driver after a controller failure. The
trace below is from a 7.0.0 based kernel, where qca_power_off() was still
named qca_power_shutdown():

Unable to handle kernel NULL pointer dereference at virtual address
0000000000000038
Call trace:
tty_set_termios+0x50/0x238 (P)
ttyport_set_baudrate+0x84/0xc0
serdev_device_set_baudrate+0x24/0x40
qca_power_shutdown+0x158/0x1fc [hci_uart]
qca_serdev_remove+0x54/0x68 [hci_uart]
serdev_drv_remove+0x1c/0x2c
device_remove+0x4c/0x80
device_release_driver_internal+0x1cc/0x224
device_driver_detach+0x18/0x24
unbind_store+0xb4/0xc0

Check HCI_UART_PROTO_READY, which hci_uart_close() clears in the same place
it closes the port, before writing to it. The regulator disable is left
unconditional so the controller is still powered down.

The dangling serport->tty that turns this into a use-after-free is
addressed in a separate patch.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Ubuntu USN Ubuntu USN USN-9019-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-9020-1 Linux kernel vulnerabilities
History
Type Values Removed Values Added
Weaknesses CWE-476
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Moderate

Type Values Removed Values Added
Weaknesses CWE-416
CWE-476
Type Values Removed Values Added
Weaknesses CWE-416
CWE-476
Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_qca: Do not write to the serial port after it is closed hci_uart_close() closes the serdev port if HCI_QUIRK_NON_PERSISTENT_SETUP is set (for example, for the WCN399x family). A failed hci_dev_open_sync() following a successful qca_setup() calls hdev->close() but not hdev->shutdown(), so the port is closed while power->vregs_on is left true. qca_serdev_remove() then passes its power->vregs_on test and calls qca_power_off(), which writes to the closed port unconditionally. Seen on a WCN3988 by unbinding the driver after a controller failure. The trace below is from a 7.0.0 based kernel, where qca_power_off() was still named qca_power_shutdown(): Unable to handle kernel NULL pointer dereference at virtual address 0000000000000038 Call trace: tty_set_termios+0x50/0x238 (P) ttyport_set_baudrate+0x84/0xc0 serdev_device_set_baudrate+0x24/0x40 qca_power_shutdown+0x158/0x1fc [hci_uart] qca_serdev_remove+0x54/0x68 [hci_uart] serdev_drv_remove+0x1c/0x2c device_remove+0x4c/0x80 device_release_driver_internal+0x1cc/0x224 device_driver_detach+0x18/0x24 unbind_store+0xb4/0xc0 Check HCI_UART_PROTO_READY, which hci_uart_close() clears in the same place it closes the port, before writing to it. The regulator disable is left unconditional so the controller is still powered down. The dangling serport->tty that turns this into a use-after-free is addressed in a separate patch.
Title Bluetooth: hci_qca: Do not write to the serial port after it is closed
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
Linux
Published
Updated
Oct 19, 2026, 9:17 AM
Reserved
Sep 25, 2026, 10:25 AM
Status
Received
Published
Oct 6, 2026, 9:18 AM
Modified
Oct 19, 2026, 10:18 AM
Severity
Moderate
Public date
Oct 6, 2026, 12:00 AM