CVE-2026-54370
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedacl 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceThe acl library before version 2.4.0 contains a TOCTOU race condition where an lstat() check of a pathname component occurs before symlink-following operations (stat(), chown(), chmod(), acl_get_file(), acl_set_file()). Local attackers who control a pathname component can replace it with a symbolic link between these operations, redirecting file ACL operations (via getfacl, setfacl, or Chacl) to arbitrary files and achieving local privilege escalation.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Local
- Complexity
- High
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check acl library versionRun 'acl-config --version' or check the installed library file (e.g., /usr/lib/libacl.so.1) and query its version through the package manager (dpkg -l libacl1, rpm -q libacl, etc.)Affected if The installed version is before 2.4.0
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Check getfacl versionRun 'getfacl --version' to see the version of the getfacl utilityAffected if The version shown is before 2.4.0
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Check setfacl versionRun 'setfacl --version' to see the version of the setfacl utilityAffected if The version shown is before 2.4.0
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Check Chac versionRun 'chacl --version' if the Chacl utility is installedAffected if The version shown is before 2.4.0 or the tool does not exist (older installation)
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Verify symlink exposureReview any scripts or automated processes that run getfacl/setfacl/chacl on paths containing components that untrusted users can modify (e.g., world-writable directories in the path)Affected if The tools are used on paths with user-controlled components and the acl library version is below 2.4.0
You are affected if the installed acl library or its utilities (getfacl, setfacl, Chac) are version 2.4.0 or lower, especially when these tools operate on paths with untrusted user-controlled components.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataUpgrade acl to version 2.4.0 or later. As a workaround, avoid running getfacl/setfacl/chacl on paths with untrusted user-controlled components.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-54370 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-54370 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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