---
id: CVE-2026-76642
title: >-
  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
summary: >-
  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…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-390
published: '2026-09-03'
updated: '2026-09-24'
sourceUpdated: '2026-09-24T20:28:01.780'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-76642'
references:
  - url: 'https://github.com/util-linux/util-linux'
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/util-linux/util-linux/blob/v2.42.2/libmount/src/context_mount.c#L476
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/util-linux/util-linux/blob/v2.42.2/libmount/src/context_mount.c#L892
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/util-linux/util-linux/commit/1d14676ea70003e9f5b2a6a76af0cadb1190411a
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/util-linux/util-linux/commit/a15c00a9e545aa8b9cf6ec0f888ff6c7b3eaeedc
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/util-linux/util-linux/commit/f57cea130839c0af8dc0525274267ae4cfd66bbf
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/util-linux/util-linux/security/advisories/GHSA-m25x-3hj9-m26f
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/util-linux-libmount-privilege-escalation-via-failed-mount-helper
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/util-linux/util-linux/security/advisories/GHSA-m25x-3hj9-m26f
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
epss: 0.00176
epssPercentile: 0.06308
ingestedAt: '2026-09-24T20:51:40.240Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.