{"id":"CVE-2026-74687","state":"PUBLISHED","title":"watchdog: at91sam9_wdt: prevent timer rearm during teardown","description":"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.","publishedAt":"2026-08-22T15:32:52.792Z","updatedAt":"2026-10-30T12:30:17.415Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"5161b31dc39a6d6dadc95f298de48a725b73ada8","status":"affected","lessThan":"f96c18a766477e5f33d51697963a5c8aed260dae","versionType":"git"},{"version":"5161b31dc39a6d6dadc95f298de48a725b73ada8","status":"affected","lessThan":"a9e0efcb1125e6b452c648671f15920c4955b681","versionType":"git"},{"version":"5161b31dc39a6d6dadc95f298de48a725b73ada8","status":"affected","lessThan":"1beb4dd6a30dea699e98990dd61f892ed1c0985e","versionType":"git"},{"version":"5161b31dc39a6d6dadc95f298de48a725b73ada8","status":"affected","lessThan":"29fe74c9aa69d78c1c6a3930f1d9fc5db71a6eed","versionType":"git"},{"version":"5161b31dc39a6d6dadc95f298de48a725b73ada8","status":"affected","lessThan":"b7949b0a7d998013b7ec8617a0ef5b07cca80be4","versionType":"git"},{"version":"5161b31dc39a6d6dadc95f298de48a725b73ada8","status":"affected","lessThan":"8444d66aa6b6e7fe0a26fa1a00a11cb4d0523783","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/watchdog/at91sam9_wdt.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.14","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.14","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.114","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.45","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.9","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/watchdog/at91sam9_wdt.c"]}],"references":["https://git.kernel.org/stable/c/f96c18a766477e5f33d51697963a5c8aed260dae","https://git.kernel.org/stable/c/a9e0efcb1125e6b452c648671f15920c4955b681","https://git.kernel.org/stable/c/1beb4dd6a30dea699e98990dd61f892ed1c0985e","https://git.kernel.org/stable/c/29fe74c9aa69d78c1c6a3930f1d9fc5db71a6eed","https://git.kernel.org/stable/c/b7949b0a7d998013b7ec8617a0ef5b07cca80be4","https://git.kernel.org/stable/c/8444d66aa6b6e7fe0a26fa1a00a11cb4d0523783"],"weaknesses":[],"ingestedAt":"2026-10-30T12:48:04.825Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/74xxx/CVE-2026-74687.json","commit":"1f312381e38164a43607eebab851b151dd16861e","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-74687","state":"PUBLISHED","datePublished":"2026-08-22T15:32:52.792Z","dateUpdated":"2026-10-30T12:30:17.415Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-15T05:44:03.926Z"},"containers":{"cna":{"title":"watchdog: at91sam9_wdt: prevent timer rearm during teardown","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":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"5161b31dc39a6d6dadc95f298de48a725b73ada8","status":"affected","lessThan":"f96c18a766477e5f33d51697963a5c8aed260dae","versionType":"git"},{"version":"5161b31dc39a6d6dadc95f298de48a725b73ada8","status":"affected","lessThan":"a9e0efcb1125e6b452c648671f15920c4955b681","versionType":"git"},{"version":"5161b31dc39a6d6dadc95f298de48a725b73ada8","status":"affected","lessThan":"1beb4dd6a30dea699e98990dd61f892ed1c0985e","versionType":"git"},{"version":"5161b31dc39a6d6dadc95f298de48a725b73ada8","status":"affected","lessThan":"29fe74c9aa69d78c1c6a3930f1d9fc5db71a6eed","versionType":"git"},{"version":"5161b31dc39a6d6dadc95f298de48a725b73ada8","status":"affected","lessThan":"b7949b0a7d998013b7ec8617a0ef5b07cca80be4","versionType":"git"},{"version":"5161b31dc39a6d6dadc95f298de48a725b73ada8","status":"affected","lessThan":"8444d66aa6b6e7fe0a26fa1a00a11cb4d0523783","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/watchdog/at91sam9_wdt.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.14","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.14","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.114","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.45","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.9","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/watchdog/at91sam9_wdt.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/f96c18a766477e5f33d51697963a5c8aed260dae"},{"url":"https://git.kernel.org/stable/c/a9e0efcb1125e6b452c648671f15920c4955b681"},{"url":"https://git.kernel.org/stable/c/1beb4dd6a30dea699e98990dd61f892ed1c0985e"},{"url":"https://git.kernel.org/stable/c/29fe74c9aa69d78c1c6a3930f1d9fc5db71a6eed"},{"url":"https://git.kernel.org/stable/c/b7949b0a7d998013b7ec8617a0ef5b07cca80be4"},{"url":"https://git.kernel.org/stable/c/8444d66aa6b6e7fe0a26fa1a00a11cb4d0523783"}],"metrics":[{"cvssV3_1":{"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"},"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":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:30:17.415Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.14","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.14","versionEndExcluding":"6.6.160"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.14","versionEndExcluding":"6.12.114"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.14","versionEndExcluding":"6.18.45"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.14","versionEndExcluding":"7.1.9"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.14","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}