# CVE-2026-76642

## Summary

- **CVE ID:** CVE-2026-76642
- **Severity:** HIGH
- **CVSS Score:** 8.5 (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)
- **CWE:** CWE-390
- **Published:** Sep 3, 2026
- **Last Modified:** Sep 3, 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.

## Affected Products

- util-linux — util-linux (2.39)
- util-linux — util-linux (2.42)

## References

- [CNA](https://github.com/util-linux/util-linux/security/advisories/GHSA-m25x-3hj9-m26f)
- [CNA](https://github.com/util-linux/util-linux/commit/f57cea130839c0af8dc0525274267ae4cfd66bbf)
- [CNA](https://github.com/util-linux/util-linux/commit/1d14676ea70003e9f5b2a6a76af0cadb1190411a)
- [CNA](https://github.com/util-linux/util-linux/commit/a15c00a9e545aa8b9cf6ec0f888ff6c7b3eaeedc)
- [CNA](https://github.com/util-linux/util-linux/blob/v2.42.2/libmount/src/context_mount.c#L476)
- [CNA](https://github.com/util-linux/util-linux/blob/v2.42.2/libmount/src/context_mount.c#L892)
- [CNA](https://github.com/util-linux/util-linux)
- [CNA](https://www.vulncheck.com/advisories/util-linux-libmount-privilege-escalation-via-failed-mount-helper)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.18%
- **EPSS Percentile:** 7.2

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-11._