{"id":"CVE-2026-112938","published":"2026-11-05T22:17:47.213","lastModified":"2026-11-05T22:17:47.213","description":"filelock is a platform-independent file lock for Python. From 3.30.0 until 4.2.1, On POSIX platforms, StrictSoftFileLock and AsyncStrictSoftFileLock validate the coordination directory in _ensure_protocol_directory but later reach the claims directory through _open_directory by pathname, allowing a local account that can rename the coordination name to swap in a symbolic link between check and use during acquisition. That race can create and leave claim files in another writable directory or strand claims in a different strict lock so the second lock times out. Separately, the claims property and force_break follow a resting symbolic link without a race when the lock user inspects or recovers the lock. Claims inspection discloses a file name to the other account only if the resulting exception text or claim_name reaches that account through a shared log, CI output, or error report. A blind force_break recovery that removes live claims from another strict lock can allow two processes into that lock's critical section; this path reaches other strict locks, not arbitrary files. This issue is fixed in version 4.2.1.","cvssScore":5.8,"cvssSeverity":"MEDIUM","cvssVector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H","cwes":["CWE-363"],"vendors":[],"products":[],"references":[{"url":"https://github.com/tox-dev/filelock/commit/aaa18595d29795fab599a69d6b184d9a505dab4b","tags":[]},{"url":"https://github.com/tox-dev/filelock/commit/bfa066d65a1ba9106f86ee9d027f7588b9c77e03","tags":[]},{"url":"https://github.com/tox-dev/filelock/pull/839","tags":[]},{"url":"https://github.com/tox-dev/filelock/releases/tag/4.2.1","tags":[]},{"url":"https://github.com/tox-dev/filelock/security/advisories/GHSA-m462-7rxw-wvpg","tags":[]}],"exploitRefs":[{"url":"https://github.com/tox-dev/filelock/commit/aaa18595d29795fab599a69d6b184d9a505dab4b","tags":[]},{"url":"https://github.com/tox-dev/filelock/commit/bfa066d65a1ba9106f86ee9d027f7588b9c77e03","tags":[]},{"url":"https://github.com/tox-dev/filelock/pull/839","tags":[]},{"url":"https://github.com/tox-dev/filelock/releases/tag/4.2.1","tags":[]},{"url":"https://github.com/tox-dev/filelock/security/advisories/GHSA-m462-7rxw-wvpg","tags":[]}],"hasPoc":true,"ai":null}