CVE-2026-112935

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

MEDIUM
4.7
CVSS Score
Published: October 20, 2026 at 02:32 PM UTC
Updated: October 28, 2026 at 03:17 PM UTC
1 product affected across 1 vendorFilelock

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Severity
MEDIUM4.7
Exploit prediction
EPSS 0.1%
SSVC
PoC

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

3.22.0 ≤ v < 4.2.1

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (4)

x_refsource_CONFIRMExploitMitigationPatchVendor Advisory
Source: cverecord
https://github.com/tox-dev/filelock/security/advisories/GHSA-fq56-3cx3-fjxp
x_refsource_MISCPatch
Source: cverecord
https://github.com/tox-dev/filelock/pull/843
x_refsource_MISCRelease Notes
Source: cverecord
https://github.com/tox-dev/filelock/releases/tag/4.2.1

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

4.7MEDIUMGitHub_M
Attack Vector
LOCAL
Complexity
HIGH
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
HIGH
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-367

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