CVE-2021-47321: Linux Kernel

High severity, CVSS 7.8. EPSS: 0.2% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: watchdog: Fix possible use-after-free by calling del_timer_sync() This driver's remove path calls del_timer(). However, that function does not wait until the timer handler finishes. This means that the timer handler may still be running after the driver's remove function has finished, which would result in a use-after-free. Fix by calling del_timer_sync(), which makes sure the timer handler has finished, and unable to re-schedule itself.

Affected products

• Linux Linux Kernel: before 4.4.276 (fixed in 4.4.276); from 4.5, before 4.9.276 (fixed in 4.9.276); from 4.10, before 4.14.240 (fixed in 4.14.240); from 4.15, before 4.19.198 (fixed in 4.19.198); from 4.20, before 5.4.134 (fixed in 5.4.134); from 5.5, before 5.10.52 (fixed in 5.10.52); …

Published 2024-05-21. Last modified 2026-06-17.