Unverified Ownership Affecting filelock package, versions [3.30.0,4.2.1)
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-PYTHON-FILELOCK-21280756
- published20 Oct 2026
- disclosed20 Oct 2026
- creditAnthropic's OSS Scanner
Introduced: 20 Oct 2026
NewCVE-2026-112911 (opens in a new tab)How to fix?
Upgrade filelock to version 4.2.1 or higher.
Overview
Affected versions of this package are vulnerable to Unverified Ownership via the strict lock implementation in _strict.py and related claim directory handling, where mkdir(mode=0o700) only enforces private permissions when it creates the directory and the subsequent lstat check reads neither st_uid nor the permission bits. A local attacker who can replace the lock's claim directory or any of its ancestors can hijack the lock, leading to integrity violations or denial of service against processes relying on the lock for mutual exclusion.
Note: This is only exploitable when another local user can replace the lock's directory or any of its ancestors.