PT-2026-30240 · Unknown · Util-Linux

T0X1Cx · Published 2026-04-03 · Updated 2026-05-20 · CVE-2026-27456

Positive Technologies (AI Summary)

CVSS v3.1

4.7

Medium

Base vector

AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N

Name of the Vulnerable Software and Affected Versions util-linux versions prior to 2.41.4

Description A Time-of-Check-Time-of-Use (TOCTOU) vulnerability exists in the SUID binary /usr/bin/mount within util-linux. When setting up loop devices, the binary validates a file path with user privileges but re-opens it with root privileges without re-verification. This allows a local user to replace the file with a symbolic link to a root-owned file or device during the race window, leading to unauthorized access to root-protected files and block devices. Exploitation requires a specific /etc/fstab configuration and the SUID bit to be set on /usr/bin/mount.

Recommendations Update to version 2.41.4 or later.

Exploit

Fix

Time Of Check To Time Of Use

Link Following

Improper Privilege Management

Weakness Enumeration

CWE-367

CWE-59

CWE-269

Related Identifiers

CVE-2026-27456

ECHO-A95F-C9F9-A568

OESA-2026-2211

OPENSUSE-SU-2026:10736-1

RHSA-2026:7180

Affected Products

Util-Linux

References · 20

• 🔥 https://github.com/util-linux/util-linux/security/advisories/GHSA-qq4x-vfq4-9h9g · Exploit
• https://github.com/util-linux/util-linux/commit/5e390467b26a3cf3fecc04e1a0d482dff3162fc4 · Patch
• https://osv.dev/vulnerability/ROOT-OS-UBUNTU-2404-CVE-2026-27456 · Vendor Advisory
• https://osv.dev/vulnerability/UBUNTU-CVE-2026-27456 · Vendor Advisory
• https://osv.dev/vulnerability/ROOT-OS-DEBIAN-13-CVE-2026-27456 · Vendor Advisory
• https://osv.dev/vulnerability/ROOT-OS-DEBIAN-12-CVE-2026-27456 · Vendor Advisory
• https://security-tracker.debian.org/tracker/CVE-2026-27456 · Vendor Advisory
• https://osv.dev/vulnerability/OESA-2026-2211 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-27456 · Security Note
• https://osv.dev/vulnerability/openSUSE-SU-2026:10736-1 · Vendor Advisory
• https://cve.org/CVERecord?id=CVE-2026-27456 · Security Note
• https://osv.dev/vulnerability/ALPINE-CVE-2026-27456 · Vendor Advisory
• https://osv.dev/vulnerability/BELL-CVE-2026-27456 · Vendor Advisory
• https://osv.dev/vulnerability/DEBIAN-CVE-2026-27456 · Vendor Advisory
• https://ubuntu.com/security/CVE-2026-27456 · Vendor Advisory