CVE-2026-112909

filelock: UnixFileLock truncates and chmods any regular file another user renames or hard-links onto the lock path

MEDIUM
6.1
CVSS Score
Published: October 20, 2026 at 02:16 PM UTC
Updated: October 27, 2026 at 09:04 PM UTC
1 product affected across 1 vendorFilelock

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Severity
MEDIUM6.1
Exploit prediction
EPSS 0.2%
SSVC
PoC

Description

filelock is a platform-independent file lock for Python. Prior to 4.2.1, UnixFileLock can truncate a regular file renamed onto the lock path when another local user has actual rename permission, or hard-linked there under a permissive hard-link policy; when an explicit mode is requested, affected versions from 3.10.2 can also change that file's mode. 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.

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-69hj-f68j-2879
x_refsource_MISCPatch
Source: cverecord
https://github.com/tox-dev/filelock/pull/835
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

6.1MEDIUMGitHub_M
Attack Vector
LOCAL
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
HIGH
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-706

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