TI-2026-76852 Aliases CVE-2026-112909 GHSA-69hj-f68j-2879

filelock UnixFileLock truncates files placed on the lock path

MEDIUM 60CWE-706Published 2026-10-20 · Updated 2026-10-22

Key facts

Attack vector: Local
Privileges required: Low
User interaction: None
Attack complexity: Low
Impact type: —
Confidentiality · integrity · availability: Low · High · None
Fix status: Partial Red Hat: 15 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA, GitHub and Red Hat.

Summary

filelock versions before 4.2.1 are affected. UnixFileLock uses a lock path that another local user has renamed or hard-linked to a regular file, which is an incorrectly resolved name (CWE-706). A local user with low privileges who has rename permission, or who can hard-link under a permissive policy, can truncate that file, and when an explicit mode is requested, affected versions from 3.10.2 can also change its mode. A public exploit is linked in the references.

Written with Claude Haiku 5.5 from the sources below · 2026-10-29

Description from the CNA

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.0022 12th percentileScored 2026-11-07

Public exploit Yes 1 exploit referenceTagged by NVD

Fix Partial filelock (tox-dev): 4.2.1filelock (PyPI): 4.2.1Red Hat: 15 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
tox-dev	filelock	before 4.2.1	4.2.1	Patch available	CNA
—	filelock (PyPI)	before 4.2.1	4.2.1	Patch available	GHSA-69hj-f68j-2879

filelock Vendortox-dev Affected before 4.2.1 Fixed in 4.2.1 Patch available CNA
filelock (PyPI) Vendor— Affected before 4.2.1 Fixed in 4.2.1 Patch available GHSA-69hj-f68j-2879

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:tox-dev:filelock::::::python::*	before 4.2.1	Vulnerable	tox-dev

cpe:2.3:a:tox-dev:filelock:*:*:*:*:*:python:*:* Versions before 4.2.1 Vulnerable ·tox-dev

Remediation

Upgrade the PyPI package filelock to version 4.2.1. Red Hat lists Ansible Automation Orchestrator 2026, Exploit Intelligence, Lightspeed Core, Lightspeed Services for Advanced Cluster Management and OpenShift Lightspeed and other products as affected without a fix. Exploit Intelligence has no fix planned.

Written with Claude Haiku 5.5 from the sources below · 2026-10-29

Fix · CNA filelock (tox-dev) Fixed in 4.2.1
Fix · GHSA-69hj-f68j-2879 filelock (PyPI) Fixed in 4.2.1 Advisory →

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

Product	Status	Plan or fix
Ansible Automation Orchestrator 2026	Affected	No fix yet: Fix deferred
Exploit Intelligence	Affected	No fix planned: Out of support scope
Lightspeed Core	Affected	No fix yet: Fix deferred
Lightspeed Services for Advanced Cluster Management	Affected	No fix yet: Fix deferred
OpenShift Lightspeed	Affected	No fix yet: Fix deferred
Pen Drive Powered by Red Hat Lightspeed	Affected	No fix yet: Fix deferred
Red Hat AI Inference Server	Affected	No fix yet: Fix deferred
Red Hat Ansible Automation Platform 2	Affected	No fix yet: Fix deferred
Red Hat Ansible Automation Platform Ansible Core 2	Affected	No fix yet: Fix deferred
Red Hat Enterprise Linux AI (RHEL AI) 3	Affected	No fix yet: Fix deferred
Red Hat Lightspeed Services for OCP	Affected	No fix yet: Fix deferred
Red Hat OpenShift AI (RHOAI)	Affected	No fix yet: Fix deferred
Red Hat OpenShift Container Platform 4	Affected	No fix yet: Fix deferred
Red Hat OpenShift Dev Spaces	Affected	No fix yet: Fix deferred
Red Hat Satellite 6	Affected	No fix yet: Fix deferred

Timeline

2026-10-20 Threatist record created from CVE-2026-112909
2026-10-21 Affected versions changed · Red Hat
2026-10-21 CVSS score added · Red Hat
2026-10-22 Priority changed: MEDIUM → LOW
2026-10-23 CISA SSVC decision points changed
2026-10-23 Priority changed: LOW → MEDIUM
2026-10-28 Alias added: GHSA-69hj-f68j-2879
2026-10-28 Fix available: PyPI/[email protected] · GHSA-69hj-f68j-2879
2026-10-28 CVSS score added · GHSA-69hj-f68j-2879
2026-10-28 Weakness changed · GHSA-69hj-f68j-2879
2026-10-28 6 new references · GHSA-69hj-f68j-2879

References

Exploit 1

https://github.com/tox-dev/filelock/security/advisories/GHSA-69hj-f68j-2879

Patch 2

Advisory 1

https://nvd.nist.gov/vuln/detail/CVE-2026-112909

Other 2

TI-2026-76862 Symlink race in filelock ReadWriteLock lets attackers overwrite files CVSS 3.1HIGH 7.1
TI-2026-76853 filelock soft locks adopt directories created by other local users CVSS 3.1MEDIUM 6.3
TI-2026-76859 Symlink following in filelock ReadWriteLock redirects SQLite database CVSS 3.1MEDIUM 6.1
TI-2026-76857 Unsafe holder record refresh in filelock SoftReadWriteLock CVSS 3.1MEDIUM 6.1
TI-2026-76856 Crafted lock database makes filelock ReadWriteLock acquisitions hang CVSS 3.1MEDIUM 5.5
TI-2026-76861 SoftFileLock in filelock trusts forged PIDs and removes live markers CVSS 3.1MEDIUM 4.7

See all 14 →

Sources

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