filelock: SoftFileLock stale-lock break removes a live lock file on a reused inode number and admits two holders

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-112935
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-20 15:17:16 UTC
Updated2026-10-20 19:50:26 UTC
Descriptionfilelock is a platform-independent file lock for Python. From 3.22.0 until 4.2.1, SoftFileLock can break a stale marker after an attacker frees its own marker following the stale read, an honest contender creates a live successor on the reused inode, and the successor's modification time is not newer than the saved observation, causing the live marker to be removed and two holders to be admitted. This issue is fixed in version 4.2.1.

Risk And Classification

Primary CVSS: v3.1 4.7 MEDIUM from [email protected]

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

Problem Types: CWE-367 | CWE-367 CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary4.7MEDIUMCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N
3.1CNADECLARED4.7MEDIUMCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N

CVSS v3.1 Breakdown

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

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Tox-dev Filelock affected >= 3.22.0, < 4.2.1 Not specified

References

ReferenceSourceLinkTags
github.com/tox-dev/filelock/releases/tag/4.2.1 [email protected] github.com
github.com/tox-dev/filelock/pull/843 [email protected] github.com
github.com/tox-dev/filelock/commit/740ff666b62a88496c8d7394e4e6230605e4d62b [email protected] github.com
github.com/tox-dev/filelock/security/advisories/GHSA-fq56-3cx3-fjxp [email protected] github.com
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