---
id: CVE-2026-78410
title: >-
  Util-linux: util-linux: restricted bind mounts do not pin the source, allowing
  x-mount.owner/group/mode redirection
summary: >-
  A flaw was found in util-linux. Restricted bind mounts take the source path
  from fstab but do not pin that source before the privileged mount. A local
  unprivileged user who can replace the authorized source or a writable ancestor
  can red…
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'
cvssSource: cna
cwe:
  - CWE-367
vendor: Red Hat
product: util-linux-main
affected:
  - util-linux-main (all versions)
  - util-linux (all versions)
  - util-linux
  - util-linux
  - rhel8/flatpak-runtime
  - rhel8/flatpak-sdk
  - util-linux
  - openshift/ose-rhel-coreos-8
  - openshift/ose-rhel-coreos-9
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-09-04T18:43:04.874138Z'
exploitAvailable: true
published: '2026-09-02'
updated: '2026-10-21'
sourceUpdated: '2026-10-21T17:51:51.633Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-78410'
references:
  - url: 'https://access.redhat.com/errata/RHSA-2026:63162'
    label: 'RHSA-2026:63162'
  - url: 'https://access.redhat.com/security/cve/CVE-2026-78410'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2522684'
    label: RHBZ#2522684
  - url: >-
      https://github.com/util-linux/util-linux/security/advisories/GHSA-rh77-686x-2f2m
tags:
  - cve.org
  - exploit-available
epss: 0.00156
epssPercentile: 0.04357
ingestedAt: '2026-10-21T18:09:27.272Z'
---

## Overview

A flaw was found in util-linux. Restricted bind mounts take the source path from fstab but do not pin that source before the privileged mount. A local unprivileged user who can replace the authorized source or a writable ancestor can redirect SUID mount(8) to bind another host directory. If the fstab entry also sets X-mount.owner, X-mount.group, or X-mount.mode, root then changes ownership or mode on that redirected inode.

## Affected

- `util-linux-main (all versions)`
- `util-linux (all versions)`
- `util-linux`
- `util-linux`
- `rhel8/flatpak-runtime`
- `rhel8/flatpak-sdk`
- `util-linux`
- `openshift/ose-rhel-coreos-8`
- `openshift/ose-rhel-coreos-9`

## Remediation

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

### Workarounds

Upgrade to util-linux v2.41.6, v2.42.3, or later. Until a fix is applied, do not allow unprivileged /etc/fstab bind or rbind entries that also specify X-mount.owner, X-mount.group, or X-mount.mode, especially when the bind source is below a user-writable ancestor.