Use-after-free in Linux kernel - CVE-2026-74687

Vulnerability details

The vulnerability allows a local user to cause a denial of service.

The vulnerability exists due to a use-after-free in the at91sam9 watchdog timer callback handling in drivers/watchdog/at91sam9_wdt.c when tearing down the driver after probe failure or device removal. A local user can trigger driver teardown while the timer callback rearms the timer to cause a denial of service.

The issue occurs because a running timer callback may continue accessing devm-allocated at91wdt memory after it has been freed.

Affected software

How to mitigate CVE-2026-74687

External References

• https://git.kernel.org/stable/c/29fe74c9aa69d78c1c6a3930f1d9fc5db71a6eed
• https://git.kernel.org/stable/c/8444d66aa6b6e7fe0a26fa1a00a11cb4d0523783
• https://git.kernel.org/stable/c/b7949b0a7d998013b7ec8617a0ef5b07cca80be4

Related Security Bulletins

• Use-after-free in Linux kernel watchdog driver