CVE-2021-47294: Linux Kernel

Medium severity, CVSS 5.5. EPSS: 0.3% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: netrom: Decrease sock refcount when sock timers expire Commit 63346650c1a9 ("netrom: switch to sock timer API") switched to use sock timer API. It replaces mod_timer() by sk_reset_timer(), and del_timer() by sk_stop_timer(). Function sk_reset_timer() will increase the refcount of sock if it is called on an inactive timer, hence, in case the timer expires, we need to decrease the refcount ourselves in the handler, otherwise, the sock refcount will be unbalanced and the sock will never be freed.

Affected products

• Linux Linux Kernel: from 4.4.173, before 4.4.277 (fixed in 4.4.277); from 4.9.155, before 4.9.277 (fixed in 4.9.277); from 4.14.98, before 4.14.241 (fixed in 4.14.241); from 4.19.20, before 4.19.199 (fixed in 4.19.199); from 5.0, before 5.4.136 (fixed in 5.4.136); from 5.5, before 5.10.54 (fixed in 5.10.54); …

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