Use of Multiple Resources with Duplicate Identifier Affecting filelock package, versions [4.1.0,4.2.1)
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-21280749
- published20 Oct 2026
- disclosed20 Oct 2026
- creditAnthropic's OSS Scanner
Introduced: 20 Oct 2026
NewCVE-2026-112906 (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 Use of Multiple Resources with Duplicate Identifier via _try_break_expired_lock and _try_break_stale_lock in _api.py and _lease.py, where an attacker with write access to the lock directory can replace a held lock file with a symlink pointing at an older file. This causes stat() to report the target's stale mtime, tricking a waiting process into breaking a live lock and allowing two processes to hold the lock simultaneously, resulting in a loss of mutual exclusion and potential data integrity compromise. The fix pins the inode before reading the marker to detect such replacements before acting on them.