CVE-2026-74687 (GCVE-0-2026-74687)

Vulnerability from cvelistv5 – Published: 2026-08-22 15:32 – Updated: 2026-08-25 05:41
VLAI
Title
watchdog: at91sam9_wdt: prevent timer rearm during teardown
Summary
In the Linux kernel, the following vulnerability has been resolved: watchdog: at91sam9_wdt: prevent timer rearm during teardown at91_ping() rearms the watchdog timer from its callback. timer_delete() neither waits for a running callback nor prevents it from rearming the timer, so probe failure or driver removal can leave the timer accessing the devm-allocated at91wdt after it has been freed. Use timer_shutdown_sync() on both teardown paths. It waits for a running callback and rejects any attempt by the callback to rearm the timer.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 5161b31dc39a6d6dadc95f298de48a725b73ada8 , < 29fe74c9aa69d78c1c6a3930f1d9fc5db71a6eed (git)
Affected: 5161b31dc39a6d6dadc95f298de48a725b73ada8 , < b7949b0a7d998013b7ec8617a0ef5b07cca80be4 (git)
Affected: 5161b31dc39a6d6dadc95f298de48a725b73ada8 , < 8444d66aa6b6e7fe0a26fa1a00a11cb4d0523783 (git)
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Linux Linux Affected: 3.14
Unaffected: 0 , < 3.14 (semver)
Unaffected: 6.18.45 , ≤ 6.18.* (semver)
Unaffected: 7.1.9 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/watchdog/at91sam9_wdt.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "versionType": "git"
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          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "3.14"
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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              "versionType": "semver"
            },
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              "version": "7.1.9",
              "versionType": "semver"
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              "versionType": "original_commit_for_fix"
            }
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        }
      ],
      "cpeApplicability": [
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          "nodes": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "versionStartIncluding": "3.14",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.9",
                  "versionStartIncluding": "3.14",
                  "vulnerable": true
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                  "versionEndExcluding": "7.2",
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                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nwatchdog: at91sam9_wdt: prevent timer rearm during teardown\n\nat91_ping() rearms the watchdog timer from its callback. timer_delete()\nneither waits for a running callback nor prevents it from rearming the\ntimer, so probe failure or driver removal can leave the timer accessing the\ndevm-allocated at91wdt after it has been freed.\n\nUse timer_shutdown_sync() on both teardown paths. It waits for a running\ncallback and rejects any attempt by the callback to rearm the timer."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The bug is in the AT91SAM9 platform watchdog driver during probe-failure cleanup or driver removal; it is reached only via local kernel/platform actions (boot probe, module load/unload, sysfs bind/unbind), not from network, Bluetooth, or physical USB/serial input paths.\nAC:L - at91_ping() unconditionally re-arms with mod_timer() while timer_delete() neither waits for the callback nor blocks rearm; an attacker who can time teardown or trigger the automatic probe-failure path can reliably race the periodic jiffies callback without uncontrollable layout or victim state.\nPR:L - Per CNA driver timer-teardown UAF precedent, once mod_timer() arms at91_ping() the callback runs autonomously; the UAF is reachable from local probe-failure cleanup or driver-removal activity on AT91 embedded/industrial targets without requiring init-namespace root privileges.\nUI:N - No victim interaction is required; the kernel timer fires on its own schedule and the use-after-free occurs during automatic init-failure teardown or driver removal, independent of opening /dev/watchdog or other user actions.\nS:U - Impact is a kernel heap/timer use-after-free within the host kernel on an embedded AT91 SoC; it does not cross VM, container, or IOMMU security boundaries.\nC:H - The at91_ping() timer callback dereferences freed at91wdt fields (next_heartbeat, wdd, heartbeat, base) after devm release, providing sprayable arbitrary kernel memory disclosure per UAF guidance.\nI:H - Reuse of the freed at91wdt lets at91_wdt_reset() issue MMIO writes through a controlled base pointer and mod_timer() corrupt timer/heap metadata, enabling arbitrary write and control-flow hijack primitives.\nA:H - Use-after-free access from the timer softirq path to freed at91wdt memory causes kernel oops or panic even without deliberate exploitation, and can be repeated by cycling probe/removal against the still-rearming timer."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-25T05:41:31.491Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/29fe74c9aa69d78c1c6a3930f1d9fc5db71a6eed"
        },
        {
          "url": "https://git.kernel.org/stable/c/b7949b0a7d998013b7ec8617a0ef5b07cca80be4"
        },
        {
          "url": "https://git.kernel.org/stable/c/8444d66aa6b6e7fe0a26fa1a00a11cb4d0523783"
        }
      ],
      "title": "watchdog: at91sam9_wdt: prevent timer rearm during teardown",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
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  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-74687",
    "datePublished": "2026-08-22T15:32:52.792Z",
    "dateReserved": "2026-08-15T05:44:03.926Z",
    "dateUpdated": "2026-08-25T05:41:31.491Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
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      "date": "2026-09-01",
      "epss": "0.00127",
      "percentile": "0.02659"
    },
    "microsoft_vex": {
      "current_release_date": "2026-08-24T14:51:49.000Z",
      "cve": "CVE-2026-74687",
      "id": "msrc_CVE-2026-74687",
      "initial_release_date": "2026-08-24T01:09:05.000Z",
      "product_status:known_affected": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "watchdog: at91sam9_wdt: prevent timer rearm during teardown",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-74687.json",
      "version": "2"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-74687\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-08-22T16:16:43.080\",\"lastModified\":\"2026-08-25T06:18:51.470\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nwatchdog: at91sam9_wdt: prevent timer rearm during teardown\\n\\nat91_ping() rearms the watchdog timer from its callback. timer_delete()\\nneither waits for a running callback nor prevents it from rearming the\\ntimer, so probe failure or driver removal can leave the timer accessing the\\ndevm-allocated at91wdt after it has been freed.\\n\\nUse timer_shutdown_sync() on both teardown paths. It waits for a running\\ncallback and rejects any attempt by the callback to rearm the timer.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"drivers/watchdog/at91sam9_wdt.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"5161b31dc39a6d6dadc95f298de48a725b73ada8\",\"lessThan\":\"29fe74c9aa69d78c1c6a3930f1d9fc5db71a6eed\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"5161b31dc39a6d6dadc95f298de48a725b73ada8\",\"lessThan\":\"b7949b0a7d998013b7ec8617a0ef5b07cca80be4\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"5161b31dc39a6d6dadc95f298de48a725b73ada8\",\"lessThan\":\"8444d66aa6b6e7fe0a26fa1a00a11cb4d0523783\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"drivers/watchdog/at91sam9_wdt.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"3.14\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"3.14\",\"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:U/C:H/I:H/A:H\",\"baseScore\":7.8,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":5.9}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/29fe74c9aa69d78c1c6a3930f1d9fc5db71a6eed\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/8444d66aa6b6e7fe0a26fa1a00a11cb4d0523783\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/b7949b0a7d998013b7ec8617a0ef5b07cca80be4\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-26T16:25:00+00:00",
      "cve": "CVE-2026-74687",
      "id": "CVE-2026-74687",
      "initial_release_date": "2026-08-22T00:00:00+00:00",
      "product_status:known_not_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: watchdog: at91sam9_wdt: prevent timer rearm during teardown",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-74687.json",
      "version": "3"
    }
  }
}



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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

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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.