Description
util-linux versions through 2.41.5 and 2.42.2 fail to check mount helper exit status before running post-mount hooks, allowing unprivileged users to execute privileged operations on pre-existing filesystems. Attackers can exploit X-mount.idmap or X-mount.owner hooks to clone filesystems with inherited suid bits or modify target inode permissions after a helper fails, achieving privilege escalation.
References9
- github.com/util-linux/util-linux
- github.com/util-linux/util-linux/blob/v2.42.2/libmount/src/cont…
- github.com/util-linux/util-linux/blob/v2.42.2/libmount/src/cont…
- github.com/util-linux/util-linux/commit/1d14676ea70003e9f5b2a6a…
- github.com/util-linux/util-linux/commit/a15c00a9e545aa8b9cf6ec0…
- github.com/util-linux/util-linux/commit/f57cea130839c0af8dc0525…
- github.com/util-linux/util-linux/security/advisories/GHSA-m25x-…
- www.vulncheck.com/advisories/util-linux-libmount-privilege-esca…
- github.com/util-linux/util-linux/security/advisories/GHSA-m25x-…
Metrics
- CVSS 3.1
-
7.8
HIGH
Score source: CNA
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - CVSS 4.0
-
8.5
HIGH
Score source: CNA
CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - EPSS — exploit probability
- 0% percentile: 12 · as of 3 November 2026
- CWE
- CWE-390
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.