CVE-2026-112911

filelock: StrictSoftFileLock and SoftReadWriteLock adopt a protocol directory another user created first, losing mutual exclusion

MEDIUM
6.3
CVSS Score
Published: October 20, 2026 at 02:21 PM UTC
Updated: October 28, 2026 at 04:17 PM UTC
1 product affected across 1 vendorFilelock

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Severity
MEDIUM6.3
Exploit prediction
EPSS 0.1%
SSVC
PoC

Description

filelock is a platform-independent file lock for Python. From 3.30.0 until 4.2.1, StrictSoftFileLock versions from 3.30.0 and SoftReadWriteLock versions from 4.0.0 can adopt a protocol directory created first by another local user in a shared parent directory, allowing that user to alter protocol state and admit concurrent holders. 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.

3.30.0 ≤ 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-9c4x-gm8v-wgc4
x_refsource_MISCPatch
Source: cverecord
https://github.com/tox-dev/filelock/pull/839
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

6.3MEDIUMGitHub_M
Attack Vector
LOCAL
Complexity
HIGH
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-283

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