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Fencer Intel
high 7.8

CVE-2026-76642 json

util-linux libmount Privilege Escalation via Failed Mount Helper

published 2mo ago modified last mo. also EUVD-2026-70382 , GHSA-m25x-3hj9-m26f

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository util-linux/util-linux. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
7.8
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 12%
public exploits
0
none known

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.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.

Patch / fix

  • util-linux util-linux 2.41.6, 2.42.3
  • util-linux Debian 14 2.42.3-1

debian advisories DEBIAN-CVE-2026-76642

  • uuidd hummingbird 1 2.42.2-3.4.hum1
  • libuuid hummingbird 1 2.42.2-3.4.hum1
  • libblkid hummingbird 1 2.42.2-3.4.hum1
  • libfdisk hummingbird 1 2.42.2-3.4.hum1
  • libmount hummingbird 1 2.42.2-3.4.hum1
  • util-linux hummingbird 1 2.42.2-3.4.hum1
  • liblastlog2 hummingbird 1 2.42.2-3.4.hum1
  • libsmartcols hummingbird 1 2.42.2-3.4.hum1

red hat advisories RHSA-2026:63162

  • 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

suse advisories SUSE-SU-2026:23861-1SUSE-SU-2026:23870-1SUSE-SU-2026:23884-1

  • util-linux openSUSE Tumbleweed 2.42.3-1.1
  • 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

opensuse advisories openSUSE-SU-2026:11870-1openSUSE-SU-2026:21905-1

  • 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-2026-76642

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 2.40.2-6

azure linux advisories AZL-99081

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

Is CVE-2026-76642 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

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-2026-76642 updated cvss 7.8

util-linux: util-linux: failed external mount helper still runs privileged X-mount post-hooks

  • Red Hat Cost Management On-Premise 1 costmanagement/costmanagement-ui-rhel10 1793825318
    fixed: vendor fix 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 RHSA-2026:93461
  • Red Hat Hardened Images uuidd 2.42.2-3.4.hum1, libuuid 2.42.2-3.4.hum1, libblkid 2.42.2-3.4.hum1, libfdisk 2.42.2-3.4.hum1, libmount 2.42.2-3.4.hum1, util-linux 2.42.2-3.4.hum1, +6 more
    fixed: vendor fix RHSA-2026:63162
  • 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 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
2mo ago

Exploit prediction

0.22% chance of exploitation in the next 30 days, higher than 12% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • github.com https://github.com/util-linux/util-linux/security/advisories/GHSA-m25x-3hj9-m26f referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 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
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CNA 4.0 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

  • util-linux util-linux

Classification

Weakness
  • CWE-390 Detection of Error Condition Without Action

References

Sources

Fencer Intel 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.

The maintainers of util-linux/util-linux published their own advisory on GitHub. Reviewed sources take precedence over it.

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