{"id":"CVE-2026-112909","title":"filelock: UnixFileLock truncates and chmods any regular file another user renames or hard-links onto the lock path","summary":"filelock is a platform-independent file lock for Python. Prior to 4.2.1, UnixFileLock can truncate a regular file renamed onto the lock path when another local user has actual rename permission, or hard-linked there under a permissive ha…","severity":"medium","cvss":6.1,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N","cvssSource":"cna","cwe":["CWE-706"],"vendor":"tox-dev","product":"filelock","affected":["filelock < 4.2.1"],"published":"2026-10-20","updated":"2026-10-20","sourceUpdated":"2026-10-20T14:16:02.317Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-112909","references":[{"url":"https://github.com/tox-dev/filelock/security/advisories/GHSA-69hj-f68j-2879","label":"https://github.com/tox-dev/filelock/security/advisories/GHSA-69hj-f68j-2879"},{"url":"https://github.com/tox-dev/filelock/pull/835","label":"https://github.com/tox-dev/filelock/pull/835"},{"url":"https://github.com/tox-dev/filelock/commit/e1e825b1992f69fb6b346dc395d5ae4893536c0a","label":"https://github.com/tox-dev/filelock/commit/e1e825b1992f69fb6b346dc395d5ae4893536c0a"},{"url":"https://github.com/tox-dev/filelock/releases/tag/4.2.1","label":"https://github.com/tox-dev/filelock/releases/tag/4.2.1"}],"tags":["cve.org"],"ingestedAt":"2026-10-20T15:09:24.129Z","slug":"CVE-2026-112909","body":"## Overview\n\nfilelock is a platform-independent file lock for Python. Prior to 4.2.1, UnixFileLock can truncate a regular file renamed onto the lock path when another local user has actual rename permission, or hard-linked there under a permissive hard-link policy; when an explicit mode is requested, affected versions from 3.10.2 can also change that file's mode. This issue is fixed in version 4.2.1.\n\n## Affected\n\n- `filelock < 4.2.1`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":34,"depthScoreParts":{"impact":33.6,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}