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🛡️ CVE-2026-27456 — util-linux

🟡 CVSS 4.7 — Medium ⚠️ Exploit Public CWE-59 NVD
4.7
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

util-linux is a random collection of Linux utilities. Prior to version 2.41.4, a TOCTOU (Time-of-Check-Time-of-Use) vulnerability has been identified in the SUID binary /usr/bin/mount from util-linux. The mount binary, when setting up loop devices, validates the source file path with user privileges via fork() + setuid() + realpath(), but subsequently re-canonicalizes and opens it with root privileges (euid=0) without verifying that the path has not been replaced between both operations. Neither O_NOFOLLOW, nor inode comparison, nor post-open fstat() are employed. This allows a local unprivileged user to replace the source file with a symlink pointing to any root-owned file or device during the race window, causing the SUID binary to open and mount it as root. Exploitation requires an /etc/fstab entry with user,loop options whose path points to a directory where the attacker has write permission, and that /usr/bin/mount has the SUID bit set (the default configuration on virtually all Linux distributions). The impact is unauthorized read access to root-protected files and block devices, including backup images, disk volumes, and any file containing a valid filesystem. This issue has been patched in version 2.41.4.

How this vulnerability can be exploited

This issue can be reached with local access to the system, attack complexity is high, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity none, availability none.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N

  • Attack vector: Local — a local account, shell or session on the host is needed.
  • Attack complexity: High — the attacker first has to win a race, learn a secret or otherwise prepare the target.
  • Privileges required: Low — an ordinary user account is enough.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: High — total loss, or loss the attacker controls.
  • Integrity impact: None.
  • Availability impact: None.

Weakness class

CVE-2026-27456 is classified as CWE-59: Link Following. The software follows symbolic or hard links without verifying their target, so a planted link can redirect an operation to a sensitive file.

Affected software

CVE-2026-27456 is recorded against 1 package.

  • util-linux (fixed in 2.41.4)

Timeline and source

Published on 3 April 2026 and last revised on 24 July 2026. A public exploit is known to exist, which raises the urgency of patching considerably. A vendor advisory or fix has been published. Record sourced from NVD.

References

github.com
github.com
github.com
github.com

Other advisories for this package

util-linux has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-59: Link Following) in other software:

Details

Severity MEDIUM
CVSS Score 4.7
CVSS Vector CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
CWE CWE-59
Public Exploit ⚠️ Yes
Source NVD
Published 2026-04-03
Updated 2026-08-20
Modified 2026-07-24

Affected Packages

Software From version Fixed in
util-linux — 2.41.4

Exploit Protection

Are you running util-linux?

CVE-2026-27456 carries CVSS 4.7 Medium rating and a public exploit already exists. BotEraser checks your installation against this and other known CVE records, and blocks IPs associated with exploit activity.

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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