SB2026082476 - Use-after-free in Linux kernel watchdog driver

Description

This security bulletin contains information about 1 vulnerability.

1) Use-after-free (CVE-ID: CVE-2026-74687)

CWE-ID: CWE-416 - Use After Free

CVSSv4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

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.

Remediation

Install update from vendor's website.

References

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