CVE-2026-53612 util-linux mount hook_owner TOCTOU allows local privilege escalation
Local attackers can exploit a race condition in the SUID mount utility to escalate privileges to root via fstab options.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-53612?
CVE-2026-53612 is a high-severity vulnerability in util-linux, published on 14 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
util-linux is a random collection of Linux utilities. In util-linux 2.39 through 2.41.4 and 2.42 through 2.42.1, the SUID `mount` utility's `hook_owner.c` post-mount hook performs path-based `chmod()` and `lchown()` operations on a previously validated mount target. A local low-privileged user authorized by an `/etc/fstab` entry with `user` or `users` and an `X-mount.mode`, `X-mount.owner`, or `X-mount.group` option can use `renameat2(RENAME_EXCHANGE)` to race a writable ancestor of the target and redirect the privileged ownership or mode change to a root-owned path, potentially gaining root privileges. This issue is fixed in 2.41.5 and 2.42.2.
Weakness: CWE-367
Which versions are affected by CVE-2026-53612?
How do I fix CVE-2026-53612?
Upgrade to a fixed version.
Is CVE-2026-53612 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-53612 exists.
Sources
Also known as ALPINE-CVE-2026-53612, AZL-108558, BELL-CVE-2026-53612, DEBIAN-CVE-2026-53612, ECHO-86fa-8a7d-d92b, GHSA-g8wm-75wr-g2vh and 1 more.