CVE-2026-54370: acl < 2.4.0 TOCTOU Symlink Traversal via getfacl/setfacl/chacl

Severity: medium (CVSS 6.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-29 · updated 2026-10-25
Weakness: CWE-367

Description

acl before version 2.4.0 contains a time-of-check to time-of-use (TOCTOU) race condition vulnerability that allows local attackers to escalate privileges by replacing a pathname component with a symbolic link between an lstat() check and subsequent symlink-following operations such as stat(), chown(), chmod(), acl_get_file(), and acl_set_file(). Attackers who control a pathname component can redirect file access control list operations to arbitrary files when getfacl, setfacl, or chacl is invoked by a privileged process over an attacker-controlled path, resulting in local privilege escalation.

Affected products

acl project acl: before 2.4.0 — fixed in 2.4.0

How to fix

Upgrade to a fixed version: acl project acl 2.4.0. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2026-54370 or the next vulnerability affects your stack