CVE-2026-74687
Received Received - Intake

Watchdog Timer Rearm Vulnerability in Linux Kernel

Publication date: 2026-08-22

Last updated on: 2026-08-22

Assigner: kernel.org

Description
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.

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Meta Information

Published
2026-08-22
Last Modified
2026-08-22
Generated
2026-08-22
AI Q&A
2026-08-22
EPSS Evaluated
N/A
NVD
CVE-2026-74687
EUVD
EUVD-2026-64374

Affected Vendors & Products

Currently, no data is known.

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability affects the Linux kernel's watchdog timer for AT91 SAM9 devices. The issue occurs when the watchdog timer's callback function re-arms the timer during teardown. If the driver is removed or fails to probe, the timer may continue accessing memory that has already been freed, leading to potential system instability or crashes.

Detection Guidance

This vulnerability is specific to the Linux kernel's watchdog subsystem, particularly the at91sam9_wdt driver. Detection requires checking the kernel version and watchdog driver status. Use commands like 'uname -a' to verify kernel version and 'lsmod | grep at91sam9_wdt' to check if the vulnerable driver is loaded.

Impact Analysis

This vulnerability could cause system crashes or instability if the watchdog timer is not properly shut down during driver removal or failure. It may lead to kernel panics or unexpected behavior in systems relying on the AT91 SAM9 watchdog timer.

Mitigation Strategies

Apply the latest kernel update that includes the fix for this vulnerability. If immediate update is not possible, consider disabling the at91sam9_wdt watchdog driver if not in use. Monitor kernel security advisories for patches.

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