Vulnerability in Util-Linux
CVE-2026-76642
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.002 (11.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 11th percentile — 11.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: +0.000
Affected products
Weakness classification (CWE)
References
- github.com/util-linux/util-linux (product)
- github.com/util-linux/util-linux/blob/v2.42.2/libmount/src/context_mount.c (technical-description)
- github.com/util-linux/util-linux/blob/v2.42.2/libmount/src/context_mount.c (technical-description)
- github.com/util-linux/util-linux/commit/1d14676ea70003e9f5b2a6a76af0cadb1190411a (patch)
- github.com/util-linux/util-linux/commit/a15c00a9e545aa8b9cf6ec0f888ff6c7b3eaeedc (patch)
- github.com/util-linux/util-linux/commit/f57cea130839c0af8dc0525274267ae4cfd66bbf (patch)
- github.com/util-linux/util-linux/security/advisories/GHSA-m25x-3hj9-m26f (vendor-advisory)
- www.vulncheck.com/advisories/util-linux-libmount-privilege-escalation-via-faile… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-76642?
- CVE-2026-76642 is a high-severity vulnerability in Util-Linux, classified under CWE-390. CVSS score: 7.8/10. Published 2026-09-03.
- How severe is CVE-2026-76642?
- High severity. CVSS v3 base score is 7.8 out of 10.