CVE-2026-53613

7.0High

Published 14 Oct 2026 · NVD status: Awaiting Analysis · AI triage by gemini-3.8-flash

7.0High

Attack vector: Local
Complexity: High
Privileges needed: Low
User interaction: None
Impact: Full C/I/A compromise
Weakness: CWE-367

Impact

A local attacker with low-privileged access can gain full root privileges. They need an /etc/fstab entry with the user or users option pointing to a target with a user-writable ancestor directory.

Root cause

A TOCTOU race condition exists where mount validates an fstab target before re-resolving the path, allowing an attacker to swap path components via renameat2 during execution.

Affected systems

util-linux 2.17 through 2.41.6, 2.42 through 2.42.3, and 2.42.4 when using the legacy mount(2) path without /proc mounted.

CVSS v3.1 · CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Fix & remediation

Upgrade util-linux past 2.42.4 and ensure /proc is mounted. As an immediate mitigation, audit /etc/fstab to remove the user and users mount options or ensure their mount targets and parent directories are only writable by root.

shell

$ sudo apt-get update && sudo apt-get install --only-upgrade util-linux

AI-suggested. Run it in staging first and check it against the vendor advisory. Why?

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NVD description

util-linux is a random collection of Linux utilities. In util-linux 2.17 through 2.41.6 and 2.42 through 2.42.3, and in 2.42.4 when the legacy `mount(2)` path is used without `/proc`, restricted non-root `mount` requests validate an `/etc/fstab` target before the mount operation re-resolves that pathname. A local low-privileged user authorized by an fstab `user` or `users` entry whose target has an attacker-writable ancestor can use `renameat2(RENAME_EXCHANGE)` to swap a path component and redirect an authorized mount to a root-owned location, such as mounting attacker-controlled content over `/etc/sudoers.d`, and thereby gain root privileges. Versions 2.41.5 and 2.42.2 pin targets for the new mount API, and 2.42.4 pins legacy targets through `/proc/self/fd`; the documented legacy fallback without `/proc` remains affected.

References

Source: nvd.nist.gov/vuln/detail/CVE-2026-53613