CVE-2026-76642
Published: September 5, 2026Last modified: October 2, 2026
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.
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score | 7.8 |
| Attack Vector | LOCAL |
| Attack complexity | LOW |
| Privileges required | LOW |
| User interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality | HIGH |
| Integrity impact | HIGH |
| Availability impact | HIGH |
| Vector | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
Notes
not applicable before https://github.com/util-linux/util-linux/commit/0bbc62dda53f9de3e9ee9b4d823d906979e337e9 (v2.39)
Status
| Product | Release | Package | Status |
|---|---|---|---|
| Alpaquita Linux | 23 LTS | util-linux | Not affected (2.38.1-r2) |
| 25 LTS | util-linux | Fixed (2.41.6-r1) | |
| Stream | util-linux | Fixed (2.42.3-r1) | |
| Hardened Containers | 23 LTS | util-linux | Not affected (2.38.1-r2) |
| 25 LTS | util-linux | Fixed (2.41.6-r1) | |
| Stream | util-linux | Fixed (2.42.3-r1) |
References
- https://github.com/util-linux/util-linux
- https://github.com/util-linux/util-linux/blob/v2.42.2/libmount/src/context_mount.c#L476
- https://github.com/util-linux/util-linux/blob/v2.42.2/libmount/src/context_mount.c#L892
- https://github.com/util-linux/util-linux/commit/1d14676ea70003e9f5b2a6a76af0cadb1190411a
- https://github.com/util-linux/util-linux/commit/a15c00a9e545aa8b9cf6ec0f888ff6c7b3eaeedc
- https://github.com/util-linux/util-linux/commit/f57cea130839c0af8dc0525274267ae4cfd66bbf
- https://github.com/util-linux/util-linux/security/advisories/GHSA-m25x-3hj9-m26f
- https://www.vulncheck.com/advisories/util-linux-libmount-privilege-escalation-via-failed-mount-helper