UNIX Hard Link Affecting filelock package, versions [4.0.0,4.2.1)
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-21280758
- published20 Oct 2026
- disclosed20 Oct 2026
- creditAnthropic's OSS Scanner
Introduced: 20 Oct 2026
NewCVE-2026-112934 (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 UNIX Hard Link via OsFiles.overwrite() in SoftReadWriteLock, which refreshes holder records by name without verifying the file identity. A local attacker who has rename access to the lock directory can replace a holder record with a named pipe to stall the lock, or, under a permissive hard-link policy, hard-link a reachable target file and cause the lock user to write through it.
Note: The hard-link vector requires a non-default kernel hard-link policy (e.g., fs.protected_hardlinks=0 on Linux, or macOS/BSD default behavior); the named-pipe vector requires rename access to the lock directory.