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CVE-2026-112939 Details

Description

filelock is a platform-independent file lock for Python. From 3.22.0 until 4.2.1, SoftFileLock can trust a forged process identifier in a marker that an attacker can modify but cannot remove, allowing an authorized contender such as another process of the holder's account or root to act as a confused deputy, remove the live marker, and admit another holder. This issue is fixed in version 4.2.1.

Metrics

CVSS 3.x Severity and Vector Strings:

CNA: [email protected]CVSS-B:4.7 MEDIUMVector:CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N

References to Advisories, Solutions, and Tools

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URL	Source(s)	Tag(s)
https://github.com/tox-dev/filelock/security/advisories/GHSA-rfpc-qcw5-3pc4	CISA-ADP	ExploitMitigationPatchVendor Advisory
https://github.com/tox-dev/filelock/commit/eeceaa846cbe4df72718d94c8371ca1ab8f5b3cc	[email protected]	Patch
https://github.com/tox-dev/filelock/pull/836	[email protected]	Patch
https://github.com/tox-dev/filelock/releases/tag/4.2.1	[email protected]	Release Notes
https://github.com/tox-dev/filelock/security/advisories/GHSA-rfpc-qcw5-3pc4	[email protected]	ExploitMitigationPatchVendor Advisory

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-345	Insufficient Verification of Data Authenticity	[email protected]

Affected Products

Product	Versions
tox-dev filelock	>= 3.22.0, < 4.2.1
CPE cpe:2.3:a:tox-dev:filelock::::::python::* Remediation No remediation found in references.

Change History

3 change records found show changes

Date	Action	Recorded By
Oct 21, 2026	Initial Analysis	[email protected]
Oct 20, 2026	CVE Modified	CISA-ADP
Oct 20, 2026	New CVE Received	[email protected]