CVE-2026-54370

Local privilege escalation via symlink replacement race

Published Jun 29, 2026 · Updated Jun 29, 2026

TOCTOU race condition in ACL before 2.4.0 allows local users to escalate privileges by replacing a pathname component with a symlink. The utilities call lstat() on each path, then perform stat(), chown(), chmod(), acl_get_file(), or acl_set_file() through pathnames that can be swapped to symlinks before use. Exploitation requires control of a pathname component and a privileged invocation of getfacl, setfacl, or chacl, enabling unauthorized ACL reads or writes to arbitrary files.

CVSS severity7.2
High
EPSS probability0.09%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

TOCTOU race condition in ACL before 2.4.0 allows local users to escalate privileges by replacing a pathname component with a symlink. The utilities call lstat() on each path, then perform stat(), chown(), chmod(), acl_get_file(), or acl_set_file() through pathnames that can be swapped to symlinks before use. Exploitation requires control of a pathname component and a privileged invocation of getfacl, setfacl, or chacl, enabling unauthorized ACL reads or writes to arbitrary files.

The record

CVE
CVE-2026-54370
Published
Jun 29, 2026
Updated
Jun 29, 2026
Vendor
ACL Project
Product
ACL
Classifications
CWE-367, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 29, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 29, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <2.4.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

ACL Project · ACLversion=0 <2.4.0

Published CVSS scores

6.3VulnCheckCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
7.2VulnCheckCVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-367Time-of-check Time-of-use (TOCTOU) Race Condition
T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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