Use of Incorrectly-Resolved Name or Reference Affecting filelock package, versions [,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.
Do your applications use this vulnerable package?
In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.
Test your applications- Snyk IDSNYK-PYTHON-FILELOCK-21280759
- published20 Oct 2026
- disclosed20 Oct 2026
- creditAnthropic's OSS Scanner
Introduced: 20 Oct 2026
NewCVE-2026-112909 (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 Incorrectly-Resolved Name or Reference via the lock-file open logic in _unix.py and related backends, where acquiring a lock on a file that does not yet exist creates it with a permissive mode (e.g. 0o666) rather than preserving the permissions of an existing lock file or applying a restrictive default. A local attacker who can observe or race the lock-file creation can read file contents that are written to the lock file (such as a SQLite journal) by a more-privileged process, or replace the lock file to redirect locking operations, achieving information disclosure and integrity impact.
Note: The protection against another local user holds only when no other user can rename entries in the lock's directory; passing a permissive explicit mode (e.g. 0o666, 0o660, 0o644) to the lock constructor also widens the exposure beyond the default truncation-only risk.