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Fencer Vulns
high 7.0

CVE-2026-53612 json

util-linux mount hook_owner TOCTOU allows local privilege escalation

published 2026-10-14 25 d ago modified 2026-10-16 23 d ago also EUVD-2026-101123

cvss
7.0
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 4%
public exploits
0
none known

Summary

util-linux is a random collection of Linux utilities. In util-linux 2.39 through 2.41.4 and 2.42 through 2.42.1, the SUID `mount` utility's `hook_owner.c` post-mount hook performs path-based `chmod()` and `lchown()` operations on a previously validated mount target. A local low-privileged user authorized by an `/etc/fstab` entry with `user` or `users` and an `X-mount.mode`, `X-mount.owner`, or `X-mount.group` option can use `renameat2(RENAME_EXCHANGE)` to race a writable ancestor of the target and redirect the privileged ownership or mode change to a root-owned path, potentially gaining root privileges. This issue is fixed in 2.41.5 and 2.42.2.

Patch / fix

  • kernel util-linux 2.41.5, 2.42.2
  • util-linux Debian 13 2.41.5-0+deb13u1
  • util-linux Debian 14 2.42.2-1

debian advisories DEBIAN-CVE-2026-53612

  • util-linux Ubuntu 24.04 LTS 2.39.3-9ubuntu6.6
  • util-linux Ubuntu 26.04 LTS 2.41.3-3ubuntu2.2

ubuntu advisories UBUNTU-CVE-2026-53612

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • util-linux SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 2.41.1-160000.5.1
  • python-libmount SLES 16.0, SLES for SAP applications 16.0 2.41.1-160000.5.1
  • util-linux-systemd SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 2.41.1-160000.5.1
  • util-linux Linux Micro 6.1 2.40.4-slfo.1.1_7.1
  • util-linux-systemd Linux Micro 6.1 2.40.4-slfo.1.1_7.1
  • util-linux SLE Module for Basesystem 15 SP7 2.40.4-150700.4.18.1
  • util-linux-systemd SLE Module for Server Applications 15 SP7, SLE Module for Basesystem 15 SP7 2.40.4-150700.4.18.1
  • util-linux Linux Micro 6.0 2.39.3-8.1

suse advisories SUSE-SU-2026:23861-1SUSE-SU-2026:23870-1SUSE-SU-2026:23884-1SUSE-SU-2026:23255-1SUSE-SU-2026:3685-1SUSE-SU-2026:3684-1

  • util-linux openSUSE Leap 16.0 2.41.1-160000.5.1
  • python-libmount openSUSE Leap 16.0 2.41.1-160000.5.1
  • util-linux-systemd openSUSE Leap 16.0 2.41.1-160000.5.1
  • util-linux openSUSE Tumbleweed 2.42.2-1.1

opensuse advisories openSUSE-SU-2026:21905-1openSUSE-SU-2026:11408-1

  • util-linux AlmaLinux 10 2.40.2-18.el10_2.20
  • uuidd AlmaLinux 10 2.40.2-18.el10_2.20
  • libuuid AlmaLinux 10 2.40.2-18.el10_2.20
  • libblkid AlmaLinux 10 2.40.2-18.el10_2.20
  • libfdisk AlmaLinux 10 2.40.2-18.el10_2.20
  • libmount AlmaLinux 10 2.40.2-18.el10_2.20
  • libsmartcols AlmaLinux 10 2.40.2-18.el10_2.20
  • util-linux-core AlmaLinux 10 2.40.2-18.el10_2.20

almalinux advisories ALSA-2026:93461

  • util-linux Rocky Linux 10 2.40.2-18.el10_2.20

rocky linux advisories RLSA-2026:93461

  • util-linux Alpine 3.23, Alpine 3.22 2.41.6-r0
  • util-linux Alpine 3.24 2.42.3-r0

alpine advisories ALPINE-CVE-2026-53612

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • util-linux Azure Linux 3.0 2.40.2-7

azure linux advisories AZL-108558

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-53612 updated cvss 7.0

util-linux: util-linux: TOCTOU in the mount program when applying post-mount ownership/mode changes

  • Red Hat Cost Management On-Premise 1 costmanagement/costmanagement-ui-rhel10 1793825318
    fixed: vendor fix “In SUID/restricted mode, reject X-mount.mode= values containing SUID/SGID bits (04000/02000). Verify mount target path ancestor chain integrity before post-hook execution.” RHSA-2026:95365
  • Red Hat Enterprise Linux AppStream (v. 10) uuidd 2.40.2-18.el10_2.20, python3-libmount 2.40.2-18.el10_2.20 Red Hat Enterprise Linux BaseOS (v. 10) libuuid 2.40.2-18.el10_2.20, libblkid 2.40.2-18.el10_2.20, libfdisk 2.40.2-18.el10_2.20, libmount 2.40.2-18.el10_2.20, util-linux 2.40.2-18.el10_2.20, libsmartcols 2.40.2-18.el10_2.20, +1 more Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libfdisk-devel 2.40.2-18.el10_2.20, uuidd-debuginfo 2.40.2-18.el10_2.20, libuuid-debuginfo 2.40.2-18.el10_2.20, libblkid-debuginfo 2.40.2-18.el10_2.20, libfdisk-debuginfo 2.40.2-18.el10_2.20, libmount-debuginfo 2.40.2-18.el10_2.20, +6 more
    fixed: vendor fix “In SUID/restricted mode, reject X-mount.mode= values containing SUID/SGID bits (04000/02000). Verify mount target path ancestor chain integrity before post-hook execution.” RHSA-2026:93461
  • Red Hat Enterprise Linux 7 uuidd, libuuid, libblkid, libmount, util-linux Red Hat Enterprise Linux 8 uuidd, libuuid, libblkid, libfdisk, libmount, util-linux, +3 more Red Hat Enterprise Linux 9 uuidd, libuuid, libblkid, libfdisk, libmount, util-linux, +6 more Red Hat Hardened Images util-linux Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8, openshift/ose-rhel-coreos-9 Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
25 d ago

Exploit prediction

0.15% chance of exploitation in the next 30 days, higher than 4% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/util-linux/util-linux/security/advisories/GHSA-g8wm-75wr-g2vh referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.0 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • util-linux util-linux

Classification

Weakness
  • CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.