Time-of-check Time-of-use (TOCTOU) Race Condition in Util-linux - CVE-2026-53613

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Main Vulnerability Database Vulnerabilities #VU146717

Time-of-check Time-of-use (TOCTOU) Race Condition in Util-linux - CVE-2026-53613

Published: September 2, 2026


Vulnerability identifier: #VU146717
CSH Severity: Low
CVSS v4: 7.3 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-53613
CWE-ID: CWE-367
Exploitation vector: Local access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a local user to escalate privileges.

The vulnerability exists due to a time-of-check time-of-use race condition in the mount target path handling in /usr/bin/mount when processing restricted non-root mount requests. A local user can atomically swap an ancestor directory of the mount target path between the permission check and the mount syscall to escalate privileges.

Exploitation requires an /etc/fstab entry with the user or users option where an ancestor directory of the mount target is writable by the attacker.


Affected software

Util-linux
openEuler
Fedora
util-linux
util-linux-help
uuidd
util-linux-user
util-linux-devel
util-linux-debugsource
util-linux-debuginfo
python-libmount
libuuid
libsmartcols
libmount
libfdisk
libblkid
python3-libmount

How to mitigate CVE-2026-53613

Install security update from vendor's website.

Util-linux - addressed in versions 2.41.5, 2.42.2
util-linux - addressed in versions 2.35.2-35, 2.37.2-56, 2.39.1-44
util-linux-help - addressed in versions 2.35.2-35, 2.37.2-56, 2.39.1-44
uuidd - addressed in versions 2.35.2-35, 2.37.2-56, 2.39.1-44
util-linux-user - addressed in versions 2.35.2-35, 2.37.2-56, 2.39.1-44
util-linux-devel - addressed in versions 2.35.2-35, 2.37.2-56, 2.39.1-44
util-linux-debugsource - addressed in versions 2.35.2-35, 2.37.2-56, 2.39.1-44
util-linux-debuginfo - addressed in versions 2.35.2-35, 2.37.2-56, 2.39.1-44
python-libmount - update to 2.35.2-35
libuuid - addressed in versions 2.35.2-35, 2.37.2-56, 2.39.1-44
libsmartcols - addressed in versions 2.35.2-35, 2.37.2-56, 2.39.1-44
libmount - addressed in versions 2.35.2-35, 2.37.2-56, 2.39.1-44
libfdisk - addressed in versions 2.35.2-35, 2.37.2-56, 2.39.1-44
libblkid - addressed in versions 2.35.2-35, 2.37.2-56, 2.39.1-44
python3-libmount - addressed in versions 2.37.2-56, 2.39.1-44
util-linux - addressed in versions 2.41.5-1.fc43, 2.41.5-1.fc44

External References

Related Security Bulletins