TI-2026-76853 Aliases CVE-2026-112911 GHSA-9c4x-gm8v-wgc4

filelock soft locks adopt directories created by other local users

MEDIUM 61CWE-283Published 2026-10-20 · Updated 2026-10-28

Key facts

Attack vector: Local
Privileges required: Low
User interaction: None
Attack complexity: High
Impact type: —
Confidentiality · integrity · availability: None · High · High
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

The filelock Python package is affected from 3.30.0 before 4.2.1, with StrictSoftFileLock affected from 3.30.0 and SoftReadWriteLock from 4.0.0. A missing ownership check (CWE-283) lets these locks adopt a protocol directory that another local user created first in a shared parent directory. A local user with low privileges can alter the protocol state and admit concurrent holders, which breaks mutual exclusion. 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. 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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.00148 4th 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	3.30.0 to before 4.2.1	4.2.1	Patch available	CNA
—	filelock (PyPI)	3.30.0 to before 4.2.1	4.2.1	Patch available	GHSA-9c4x-gm8v-wgc4

filelock Vendortox-dev Affected 3.30.0 to before 4.2.1 Fixed in 4.2.1 Patch available CNA
filelock (PyPI) Vendor— Affected 3.30.0 to before 4.2.1 Fixed in 4.2.1 Patch available GHSA-9c4x-gm8v-wgc4

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:tox-dev:filelock::::::python::*	3.30.0 to before 4.2.1	Vulnerable	tox-dev

cpe:2.3:a:tox-dev:filelock:*:*:*:*:*:python:*:* Versions 3.30.0 to before 4.2.1 Vulnerable ·tox-dev

Remediation

Fix the PyPI filelock package by moving to version 4.2.1. Red Hat lists no available fix for Ansible Automation Orchestrator 2026, Lightspeed Core, Lightspeed Services for Advanced Cluster Management, OpenShift Lightspeed and other products, and Red Hat plans no fix for Exploit Intelligence.

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-9c4x-gm8v-wgc4 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-2026-112911
2026-10-21 Affected versions changed · Red Hat
2026-10-21 CVSS score added · Red Hat
2026-10-22 Priority changed: MEDIUM → LOW
2026-10-28 CISA SSVC decision points changed
2026-10-28 Priority changed: LOW → MEDIUM
2026-10-28 Alias added: GHSA-9c4x-gm8v-wgc4
2026-10-28 Fix available: PyPI/[email protected] · GHSA-9c4x-gm8v-wgc4
2026-10-28 CVSS score added · GHSA-9c4x-gm8v-wgc4
2026-10-28 Weakness changed · GHSA-9c4x-gm8v-wgc4
2026-10-28 6 new references · GHSA-9c4x-gm8v-wgc4

References

Exploit 1

https://github.com/tox-dev/filelock/security/advisories/GHSA-9c4x-gm8v-wgc4

Patch 2

Advisory 1

https://nvd.nist.gov/vuln/detail/CVE-2026-112911

Other 2

TI-2026-76862 Symlink race in filelock ReadWriteLock lets attackers overwrite files CVSS 3.1HIGH 7.1
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-2026-76852 filelock UnixFileLock truncates files placed on the lock path 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

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences