filelock: UnixFileLock truncates and chmods any regular file another user renames or hard-links onto the lock path

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-112909
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-20 15:17:15 UTC
Updated2026-10-20 19:50:26 UTC
Descriptionfilelock 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.

Risk And Classification

Primary CVSS: v3.1 6.1 MEDIUM from [email protected]

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N

Problem Types: CWE-706 | CWE-706 CWE-706: Use of Incorrectly-Resolved Name or Reference

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary6.1MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N
3.1CNADECLARED6.1MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
High
Availability
None

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Tox-dev Filelock affected < 4.2.1 Not specified

References

ReferenceSourceLinkTags
github.com/tox-dev/filelock/security/advisories/GHSA-69hj-f68j-2879 [email protected] github.com
github.com/tox-dev/filelock/releases/tag/4.2.1 [email protected] github.com
github.com/tox-dev/filelock/commit/e1e825b1992f69fb6b346dc395d5ae4893536c0a [email protected] github.com
github.com/tox-dev/filelock/pull/835 [email protected] github.com
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