Linux Kernel at91sam9_wdt at91sam9_wdt.c at91_ping use after free

Summaryinfo

A vulnerability categorized as very critical has been discovered in Linux Kernel. This issue affects the function at91_ping of the file at91sam9_wdt.c of the component at91sam9_wdt. Executing a manipulation can lead to use after free. This vulnerability is handled as CVE-2026-74687. It is possible to launch the attack on the local host. There is not any exploit available.

Detailsinfo

A vulnerability was found in Linux Kernel (affected version unknown). It has been declared as very critical. This vulnerability affects the function at91_ping of the file at91sam9_wdt.c of the component at91sam9_wdt. The manipulation with an unknown input leads to a use after free vulnerability. The CWE definition for the vulnerability is CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is available at git.kernel.org. This vulnerability was named CVE-2026-74687 since 08/15/2026. The exploitation appears to be easy. Local access is required to approach this attack. The exploitation needs additional levels of successful authentication. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 08/22/2026).

Applying the patch 29fe74c9aa69d78c1c6a3930f1d9fc5db71a6eed/b7949b0a7d998013b7ec8617a0ef5b07cca80be4/8444d66aa6b6e7fe0a26fa1a00a11cb4d0523783 is able to eliminate this problem.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

License

• open-source

Website

• Vendor: https://www.kernel.org/

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