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.
References8
- github.com/util-linux/util-linux/commit/24da33905c7115c4cbccd0a…
- github.com/util-linux/util-linux/commit/722c96974dd4009a334e4ae…
- github.com/util-linux/util-linux/commit/897a08c2b11dfa66975c3d2…
- github.com/util-linux/util-linux/commit/d0c5adaeb3a3d823aba1377…
- github.com/util-linux/util-linux/releases/tag/v2.41.5
- github.com/util-linux/util-linux/releases/tag/v2.42.2
- github.com/util-linux/util-linux/security/advisories/GHSA-g8wm-…
- github.com/util-linux/util-linux/security/advisories/GHSA-g8wm-…
Metrics
- CVSS 3.1
-
7.0
HIGH
Score source: CNA
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H - EPSS — exploit probability
- 0% percentile: 4 · as of 11 November 2026
- CWE
- CWE-367
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.