filelock is a platform-independent file lock for Python. From version 3.30.0 until version 4.2.1,  StrictSoftFileLock  and  AsyncStrictSoftFileLock  on POSIX systems create coordination and claim directories without applying the caller’s restrictive lock mode. A permissive umask or inherited default ACL can leave these directories writable by another local user, allowing that user to delete an active holder’s claims. Another authorized process can then acquire the lock while the original holder remains in its critical section. An attacker can also plant malformed claims to prevent acquisition. This issue is fixed in version 4.2.1.
History

Fri, 06 Nov 2026 12:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-279
References
Metrics threat_severity

None

threat_severity

Moderate


Fri, 06 Nov 2026 00:00:00 +0000

Type Values Removed Values Added
First Time appeared Tox-dev
Tox-dev filelock
Vendors & Products Tox-dev
Tox-dev filelock

Thu, 05 Nov 2026 22:15:00 +0000

Type Values Removed Values Added
Description filelock is a platform-independent file lock for Python. From version 3.30.0 until version 4.2.1,  StrictSoftFileLock  and  AsyncStrictSoftFileLock  on POSIX systems create coordination and claim directories without applying the caller’s restrictive lock mode. A permissive umask or inherited default ACL can leave these directories writable by another local user, allowing that user to delete an active holder’s claims. Another authorized process can then acquire the lock while the original holder remains in its critical section. An attacker can also plant malformed claims to prevent acquisition. This issue is fixed in version 4.2.1.
Title filelock: StrictSoftFileLock creates its claim directories without the lock mode, so another local user with a write bit on them can end a live hold
Weaknesses CWE-732
References
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:L'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published: 2026-11-05T21:54:53.585Z

Updated: 2026-11-05T21:54:53.585Z

Reserved: 2026-10-19T20:16:09.857Z

Link: CVE-2026-112908

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-11-05T22:17:46.693

Modified: 2026-11-06T21:40:43.450

Link: CVE-2026-112908

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-11-05T21:54:53Z

Links: CVE-2026-112908 - Bugzilla