CVE-2026-74655 (GCVE-0-2026-74655)

Vulnerability from cvelistv5 – Published: 2026-08-22 15:32 – Updated: 2026-08-27 12:39
VLAI
Title
serial: qcom-geni: fix TX DMA buffer flush
Summary
In the Linux kernel, the following vulnerability has been resolved: serial: qcom-geni: fix TX DMA buffer flush When transmit flushing a qcom-geni UART during an ongoing TX DMA, the UART gets stuck infinitely repeating corrupted TX DMA frames. The DMA-mode uart_ops does not provide a flush_buffer callback, so an in-flight transfer can complete after serial core has reset the transmit kfifo, underflowing its length and resubmitting page-sized transfers indefinitely. Add one that stops the transfer and clears tx_remaining and tx_queued. The stop path was also broken: it unmapped the buffer while the serial engine could still read it, and never reset the TX DMA state machine. Cancel the main sequencer command first, then reset the state machine and wait for it before unmapping. Drop the early return so a pending mapping is also cleaned up when the main command is inactive. The bug can be triggered from userspace with a large write immediately followed by TCOFLUSH. A following tcdrain will hang forever. The bug was reproduced and this fix was validated on Arduino Uno Q (QRB2210) using /dev/ttyHS1.
Severity
8.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 2aaa43c7077833301c237684cd7bc9ae5e3dec95 , < 1606abb7ce8c0cfef98c7e556b83c14e5d73c1bf (git)
Affected: 2aaa43c7077833301c237684cd7bc9ae5e3dec95 , < 313ae287442e5e8d3f7b53b73f37d384bda072d0 (git)
Affected: 2aaa43c7077833301c237684cd7bc9ae5e3dec95 , < 1c31e2377f4c1bb110ca7f6e597b2253a7440c37 (git)
Affected: 2aaa43c7077833301c237684cd7bc9ae5e3dec95 , < b1801c0d40f62778b613334de5840aba10a564d5 (git)
Affected: 2aaa43c7077833301c237684cd7bc9ae5e3dec95 , < e3c04834ae1ab5e9cfbe8ac54ec734aa4774249d (git)
guessed Create a notification for this product.
Linux Linux Affected: 6.3
Unaffected: 0 , < 6.3 (semver)
Unaffected: 6.6.154 , ≤ 6.6.* (semver)
Unaffected: 6.12.104 , ≤ 6.12.* (semver)
Unaffected: 6.18.45 , ≤ 6.18.* (semver)
Unaffected: 7.1.9 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "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"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.154",
                  "versionStartIncluding": "6.3",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.104",
                  "versionStartIncluding": "6.3",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.45",
                  "versionStartIncluding": "6.3",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.9",
                  "versionStartIncluding": "6.3",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "6.3",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "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": {
            "baseScore": 8.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
            "version": "3.1"
          },
          "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."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-27T12:39:56.189Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "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"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-74655",
    "datePublished": "2026-08-22T15:32:29.993Z",
    "dateReserved": "2026-08-15T05:44:03.923Z",
    "dateUpdated": "2026-08-27T12:39:56.189Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-74655",
      "date": "2026-08-29",
      "epss": "0.00129",
      "percentile": "0.02798"
    },
    "microsoft_vex": {
      "current_release_date": "2026-08-24T14:44:08.000Z",
      "cve": "CVE-2026-74655",
      "id": "msrc_CVE-2026-74655",
      "initial_release_date": "2026-08-24T01:10:41.000Z",
      "product_status:known_affected": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "serial: qcom-geni: fix TX DMA buffer flush",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-74655.json",
      "version": "2"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-74655\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-08-22T16:16:39.067\",\"lastModified\":\"2026-08-27T13:18:35.997\",\"vulnStatus\":\"Received\",\"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.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"drivers/tty/serial/qcom_geni_serial.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"2aaa43c7077833301c237684cd7bc9ae5e3dec95\",\"lessThan\":\"1606abb7ce8c0cfef98c7e556b83c14e5d73c1bf\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"2aaa43c7077833301c237684cd7bc9ae5e3dec95\",\"lessThan\":\"313ae287442e5e8d3f7b53b73f37d384bda072d0\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"2aaa43c7077833301c237684cd7bc9ae5e3dec95\",\"lessThan\":\"1c31e2377f4c1bb110ca7f6e597b2253a7440c37\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"2aaa43c7077833301c237684cd7bc9ae5e3dec95\",\"lessThan\":\"b1801c0d40f62778b613334de5840aba10a564d5\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"2aaa43c7077833301c237684cd7bc9ae5e3dec95\",\"lessThan\":\"e3c04834ae1ab5e9cfbe8ac54ec734aa4774249d\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"drivers/tty/serial/qcom_geni_serial.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"6.3\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"6.3\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.154\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.104\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.45\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.9\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"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\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"CHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":2.0,\"impactScore\":6.0}]},\"references\":[{\"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\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-25T08:53:20+00:00",
      "cve": "CVE-2026-74655",
      "id": "CVE-2026-74655",
      "initial_release_date": "2026-08-22T00:00:00+00:00",
      "product_status:known_affected": "76",
      "product_status:known_not_affected": "198",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: serial: qcom-geni: fix TX DMA buffer flush",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-74655.json",
      "version": "3"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.