Skip to content
Fencer Vulns
high 7.8

CVE-2026-76642 json

util-linux libmount Privilege Escalation via Failed Mount Helper

published 2026-09-03 2 mo ago modified 2026-09-24 45 d ago also EUVD-2026-70382

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

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
2 mo ago

Exploit prediction

0.22% chance of exploitation in the next 30 days, higher than 12% of all scored CVEs (FIRST EPSS, 2026-11-08).

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 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.