CVE-2026-54370: Time-of-check Time-of-use (TOCTOU) Race Condition in acl project acl
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.
AI Analysis
Technical Summary
The acl project before version 2.4.0 contains a TOCTOU race condition vulnerability. Local attackers can exploit this by replacing a pathname component with a symbolic link between the time the system checks the file status (lstat()) and when it uses the file (stat(), chown(), chmod(), acl_get_file(), acl_set_file()). This allows attackers controlling a pathname component to redirect privileged file ACL operations to arbitrary files, resulting in local privilege escalation. The vulnerability has a CVSS 4.0 base score of 7.2, indicating high severity, with attack vector local, high attack complexity, and high impact on confidentiality and integrity.
Potential Impact
Local attackers with the ability to control pathname components can escalate privileges by redirecting privileged ACL operations to arbitrary files. This can lead to unauthorized modification or disclosure of file access control lists, potentially compromising system security and integrity.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or temporary workaround is currently documented. Until a patch is available, avoid running getfacl, setfacl, or chacl on untrusted or attacker-controlled paths with elevated privileges.
CVE-2026-54370: Time-of-check Time-of-use (TOCTOU) Race Condition in acl project acl
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.
CVSS v4.0
Score 7.2high
Affected software
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The acl project before version 2.4.0 contains a TOCTOU race condition vulnerability. Local attackers can exploit this by replacing a pathname component with a symbolic link between the time the system checks the file status (lstat()) and when it uses the file (stat(), chown(), chmod(), acl_get_file(), acl_set_file()). This allows attackers controlling a pathname component to redirect privileged file ACL operations to arbitrary files, resulting in local privilege escalation. The vulnerability has a CVSS 4.0 base score of 7.2, indicating high severity, with attack vector local, high attack complexity, and high impact on confidentiality and integrity.
Potential Impact
Local attackers with the ability to control pathname components can escalate privileges by redirecting privileged ACL operations to arbitrary files. This can lead to unauthorized modification or disclosure of file access control lists, potentially compromising system security and integrity.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or temporary workaround is currently documented. Until a patch is available, avoid running getfacl, setfacl, or chacl on untrusted or attacker-controlled paths with elevated privileges.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-06-12T20:20:02.948Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a4274e827e9c79719eeb13f
Added to database: 06/29/2026, 13:36:40 UTC
Last enriched: 07/15/2026, 10:11:59 UTC
Last updated: 08/13/2026, 12:41:10 UTC
Views: 101
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