CVE-2026-74655

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-74655", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-15T05:44:03.923Z", "datePublished": "2026-08-22T15:32:29.993Z", "dateUpdated": "2026-08-27T12:39:56.189Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-27T12:39:56.189Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nserial: qcom-geni: fix TX DMA buffer flush\n\nWhen transmit flushing a qcom-geni UART during an ongoing TX DMA, the\nUART gets stuck infinitely repeating corrupted TX DMA frames.\n\nThe DMA-mode uart_ops does not provide a flush_buffer callback, so an\nin-flight transfer can complete after serial core has reset the transmit\nkfifo, underflowing its length and resubmitting page-sized transfers\nindefinitely. Add one that stops the transfer and clears tx_remaining\nand tx_queued.\n\nThe stop path was also broken: it unmapped the buffer while the serial\nengine could still read it, and never reset the TX DMA state machine.\nCancel the main sequencer command first, then reset the state machine\nand wait for it before unmapping. Drop the early return so a pending\nmapping is also cleaned up when the main command is inactive.\n\nThe bug can be triggered from userspace with a large write immediately\nfollowed by TCOFLUSH. A following tcdrain will hang forever. The bug was\nreproduced and this fix was validated on Arduino Uno Q (QRB2210)\nusing /dev/ttyHS1."}], "metrics": [{"cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H", "baseScore": 8.8, "baseSeverity": "HIGH"}, "scenarios": [{"lang": "en", "value": "AV:L - Exploitation requires local write(2) and tcflush(TCOFLUSH)/tcdrain() ioctls on a Qualcomm GENI DMA UART (/dev/ttyHS*), reachable only through local TTY device-node syscalls, not over a network protocol.\nAC:L - The attacker fully controls timing by issuing a large write during active TX DMA immediately followed by TCOFLUSH; no races or external victim state beyond concurrent DMA completion are required to reproduce the hang and DMA loop.\nPR:L - Triggering the bug needs only permission to open, write, and ioctl an assigned ttyHS serial port (typically dialout-group or embedded-app access on Qualcomm/Android/IoT targets), not init-namespace root or CAP_SYS_ADMIN.\nUI:N - No victim interaction is required; the attacker directly drives the vulnerable flush path with their own write and TCOFLUSH/tcdrain calls on the serial device they already control.\nS:C - The flawed stop path unmaps the TX DMA buffer while the GENI engine can still read it and without resetting the TX DMA FSM, crossing the kernel/DMA hardware memory boundary and allowing the device to access host memory outside the intended mapping.\nC:H - Stale page-sized DMA retransmissions can leak residual kernel data from the UART xmit buffer and adjacent heap, and post-unmap DMA reads can expose arbitrary remapped physical memory to the serial line or driver state.\nI:H - Missing flush handling leaves tx_remaining/tx_dma_addr inconsistent with a reset kfifo, enabling kfifo pointer underflow and uncontrolled DMA from wrong offsets that corrupt kernel memory and driver bookkeeping.\nA:H - The UART enters an infinite loop of corrupted TX DMA frames and tcdrain/tty_wait_until_sent never completes, causing permanent hang of processes draining the port and sustained denial of the serial subsystem."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["drivers/tty/serial/qcom_geni_serial.c"], "versions": [{"version": "2aaa43c7077833301c237684cd7bc9ae5e3dec95", "lessThan": "1606abb7ce8c0cfef98c7e556b83c14e5d73c1bf", "status": "affected", "versionType": "git"}, {"version": "2aaa43c7077833301c237684cd7bc9ae5e3dec95", "lessThan": "313ae287442e5e8d3f7b53b73f37d384bda072d0", "status": "affected", "versionType": "git"}, {"version": "2aaa43c7077833301c237684cd7bc9ae5e3dec95", "lessThan": "1c31e2377f4c1bb110ca7f6e597b2253a7440c37", "status": "affected", "versionType": "git"}, {"version": "2aaa43c7077833301c237684cd7bc9ae5e3dec95", "lessThan": "b1801c0d40f62778b613334de5840aba10a564d5", "status": "affected", "versionType": "git"}, {"version": "2aaa43c7077833301c237684cd7bc9ae5e3dec95", "lessThan": "e3c04834ae1ab5e9cfbe8ac54ec734aa4774249d", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["drivers/tty/serial/qcom_geni_serial.c"], "versions": [{"version": "6.3", "status": "affected"}, {"version": "0", "lessThan": "6.3", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.154", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.104", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.45", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.1.9", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.3", "versionEndExcluding": "6.6.154"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.3", "versionEndExcluding": "6.12.104"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.3", "versionEndExcluding": "6.18.45"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.3", "versionEndExcluding": "7.1.9"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.3", "versionEndExcluding": "7.2"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/1606abb7ce8c0cfef98c7e556b83c14e5d73c1bf"}, {"url": "https://git.kernel.org/stable/c/313ae287442e5e8d3f7b53b73f37d384bda072d0"}, {"url": "https://git.kernel.org/stable/c/1c31e2377f4c1bb110ca7f6e597b2253a7440c37"}, {"url": "https://git.kernel.org/stable/c/b1801c0d40f62778b613334de5840aba10a564d5"}, {"url": "https://git.kernel.org/stable/c/e3c04834ae1ab5e9cfbe8ac54ec734aa4774249d"}], "title": "serial: qcom-geni: fix TX DMA buffer flush", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["drivers/tty/serial/qcom_geni_serial.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "1606abb7ce8c0cfef98c7e556b83c14e5d73c1bf", "status": "affected", "version": "2aaa43c7077833301c237684cd7bc9ae5e3dec95", "versionType": "git"}, {"lessThan": "313ae287442e5e8d3f7b53b73f37d384bda072d0", "status": "affected", "version": "2aaa43c7077833301c237684cd7bc9ae5e3dec95", "versionType": "git"}, {"lessThan": "1c31e2377f4c1bb110ca7f6e597b2253a7440c37", "status": "affected", "version": "2aaa43c7077833301c237684cd7bc9ae5e3dec95", "versionType": "git"}, {"lessThan": "b1801c0d40f62778b613334de5840aba10a564d5", "status": "affected", "version": "2aaa43c7077833301c237684cd7bc9ae5e3dec95", "versionType": "git"}, {"lessThan": "e3c04834ae1ab5e9cfbe8ac54ec734aa4774249d", "status": "affected", "version": "2aaa43c7077833301c237684cd7bc9ae5e3dec95", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["drivers/tty/serial/qcom_geni_serial.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "6.3"}, {"lessThan": "6.3", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "6.6.*", "status": "unaffected", "version": "6.6.154", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.104", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.45", "versionType": "semver"}, {"lessThanOrEqual": "7.1.*", "status": "unaffected", "version": "7.1.9", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.2", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nserial: qcom-geni: fix TX DMA buffer flush\n\nWhen transmit flushing a qcom-geni UART during an ongoing TX DMA, the\nUART gets stuck infinitely repeating corrupted TX DMA frames.\n\nThe DMA-mode uart_ops does not provide a flush_buffer callback, so an\nin-flight transfer can complete after serial core has reset the transmit\nkfifo, underflowing its length and resubmitting page-sized transfers\nindefinitely. Add one that stops the transfer and clears tx_remaining\nand tx_queued.\n\nThe stop path was also broken: it unmapped the buffer while the serial\nengine could still read it, and never reset the TX DMA state machine.\nCancel the main sequencer command first, then reset the state machine\nand wait for it before unmapping. Drop the early return so a pending\nmapping is also cleaned up when the main command is inactive.\n\nThe bug can be triggered from userspace with a large write immediately\nfollowed by TCOFLUSH. A following tcdrain will hang forever. The bug was\nreproduced and this fix was validated on Arduino Uno Q (QRB2210)\nusing /dev/ttyHS1."}, {"lang": "es", "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nserial: qcom-geni: corregir el vaciado del b\u00fafer DMA de TX\n\nAl vaciar la transmisi\u00f3n de una UART qcom-geni durante un DMA de TX en curso, la UART se queda atascada repitiendo infinitamente tramas DMA de TX corruptas.\n\nLas uart_ops en modo DMA no proporcionan una funci\u00f3n de devoluci\u00f3n de llamada flush_buffer, por lo que una transferencia en curso puede completarse despu\u00e9s de que el n\u00facleo serie haya reiniciado el kfifo de transmisi\u00f3n, causando un desbordamiento negativo de su longitud y reenviando transferencias de tama\u00f1o de p\u00e1gina indefinidamente. A\u00f1adir una que detenga la transferencia y borre tx_remaining y tx_queued.\n\nLa ruta de parada tambi\u00e9n estaba rota: desmapeaba el b\u00fafer mientras el motor serie a\u00fan pod\u00eda leerlo, y nunca reiniciaba la m\u00e1quina de estados del DMA de TX. Cancelar primero el comando principal del secuenciador, luego reiniciar la m\u00e1quina de estados y esperar a que termine antes de desmapear. Eliminar el retorno anticipado para que un mapeo pendiente tambi\u00e9n se limpie cuando el comando principal est\u00e9 inactivo.\n\nEl error puede ser provocado desde el espacio de usuario con una escritura grande inmediatamente seguida por TCOFLUSH. Un tcdrain posterior se colgar\u00e1 para siempre. El error fue reproducido y esta correcci\u00f3n fue validada en Arduino Uno Q (QRB2210) usando /dev/ttyHS1."}], "id": "CVE-2026-74655", "lastModified": "2026-10-14T13:10:00.187", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 8.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "CHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 2.0, "impactScore": 6.0, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}]}, "published": "2026-08-22T16:16:39.067", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/1606abb7ce8c0cfef98c7e556b83c14e5d73c1bf"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/1c31e2377f4c1bb110ca7f6e597b2253a7440c37"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/313ae287442e5e8d3f7b53b73f37d384bda072d0"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/b1801c0d40f62778b613334de5840aba10a564d5"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/e3c04834ae1ab5e9cfbe8ac54ec734aa4774249d"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: serial: qcom-geni: fix TX DMA buffer flush", "id": "2521448", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2521448"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.5", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-835", "details": ["In the Linux kernel, the following vulnerability has been resolved:\nserial: qcom-geni: fix TX DMA buffer flush\nWhen transmit flushing a qcom-geni UART during an ongoing TX DMA, the\nUART gets stuck infinitely repeating corrupted TX DMA frames.\nThe DMA-mode uart_ops does not provide a flush_buffer callback, so an\nin-flight transfer can complete after serial core has reset the transmit\nkfifo, underflowing its length and resubmitting page-sized transfers\nindefinitely. Add one that stops the transfer and clears tx_remaining\nand tx_queued.\nThe stop path was also broken: it unmapped the buffer while the serial\nengine could still read it, and never reset the TX DMA state machine.\nCancel the main sequencer command first, then reset the state machine\nand wait for it before unmapping. Drop the early return so a pending\nmapping is also cleaned up when the main command is inactive.\nThe bug can be triggered from userspace with a large write immediately\nfollowed by TCOFLUSH. A following tcdrain will hang forever. The bug was\nreproduced and this fix was validated on Arduino Uno Q (QRB2210)\nusing /dev/ttyHS1.", "A flaw was found in the Linux kernel. Specifically, a vulnerability exists in the `qcom-geni` Universal Asynchronous Receiver-Transmitter (UART) driver's transmit Direct Memory Access (DMA) buffer flush mechanism. A local user can exploit this by initiating a large write operation immediately followed by a `TCOFLUSH` command. This can cause the UART to become unresponsive, leading to an indefinite hang during subsequent `tcdrain` calls and resulting in a Denial of Service (DoS)."], "name": "CVE-2026-74655", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-08-22T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-74655\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-74655\nhttps://lore.kernel.org/linux-cve-announce/2026082226-CVE-2026-74655-093d@gregkh/T"], "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[2aaa43c7077833301c237684cd7bc9ae5e3dec95,313ae287442e5e8d3f7b53b73f37d384bda072d0)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[2aaa43c7077833301c237684cd7bc9ae5e3dec95,1c31e2377f4c1bb110ca7f6e597b2253a7440c37)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[2aaa43c7077833301c237684cd7bc9ae5e3dec95,b1801c0d40f62778b613334de5840aba10a564d5)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[2aaa43c7077833301c237684cd7bc9ae5e3dec95,e3c04834ae1ab5e9cfbe8ac54ec734aa4774249d)"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "6.3"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[0,6.3)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[6.12.104,6.13.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[6.18.45,6.19.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.1.9,7.2.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.2,*]"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}], "created": "2026-08-22T17:00:10.931468+00:00", "updated": "2026-08-25T17:30:07.655922+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}