CVE-2026-112935

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

Published Oct 20, 2026 CVSS 3.1 · 4.7 Medium EPSS < 1% KEV · Not listed
Description
filelock 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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-fq56-3cx3-fjxp filelock: SoftFileLock stale-lock break removes a live lock file on a reused inode number and admits two holders
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
CPEs cpe:2.3:a:tox-dev:filelock:*:*:*:*:*:python:*:*
Type Values Removed Values Added
First Time appeared Tox-dev
Tox-dev filelock
Vendors & Products Tox-dev
Tox-dev filelock
Type Values Removed Values Added
Description filelock 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.
Title filelock: SoftFileLock stale-lock break removes a live lock file on a reused inode number and admits two holders
Weaknesses CWE-367
References
Metrics cvssV3_1

{'score': 4.7, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Oct 28, 2026, 2:17 PM
Reserved
Oct 19, 2026, 9:30 PM
Status
Modified
Published
Oct 20, 2026, 3:17 PM
Modified
Oct 28, 2026, 3:17 PM
Severity
Moderate
Public date
Oct 20, 2026, 2:32 PM