TI-2026-76851 Aliases CVE-2026-112906 GHSA-2g95-wg33-c5x2

Race condition in filelock SoftFileLock evicts live lock markers

MEDIUM 55CWE-694Published 2026-10-20 · Updated 2026-10-20

Key facts

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

The filelock Python package, from version 4.1.0 before 4.2.1, is affected through its SoftFileLock class. A race condition (CWE-362) lets a reused file inode be treated as a stale lock marker, so a live marker created by an honest process is removed. A local user with low privileges can trigger this when at least two lock-user processes are waiting, and a public exploit is linked in the references.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

Description from the CNA

filelock is a platform-independent file lock for Python. From 4.1.0 until 4.2.1, SoftFileLock versions from 4.1.0 can reuse a stale observation when an attacker pre-dates and removes its own marker, at least two lock-user processes are waiting, coarse or matching modification times preserve the observation, and an honest contender creates a fresh marker on the reused inode, causing that live marker to be removed as stale. This issue is fixed in version 4.2.1.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.00168 6th 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	4.1.0 to before 4.2.1	4.2.1	Patch available	CNA
—	filelock (PyPI)	4.1.0 to before 4.2.1	4.2.1	Patch available	GHSA-2g95-wg33-c5x2

filelock Vendortox-dev Affected 4.1.0 to before 4.2.1 Fixed in 4.2.1 Patch available CNA
filelock (PyPI) Vendor— Affected 4.1.0 to before 4.2.1 Fixed in 4.2.1 Patch available GHSA-2g95-wg33-c5x2

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:tox-dev:filelock::::::python::*	4.1.0 to before 4.2.1	Vulnerable	tox-dev

cpe:2.3:a:tox-dev:filelock:*:*:*:*:*:python:*:* Versions 4.1.0 to before 4.2.1 Vulnerable ·tox-dev

Remediation

Upgrade the filelock package on PyPI to version 4.2.1. The sources list no fixed version for Ansible Automation Orchestrator 2026, Exploit Intelligence, Lightspeed Core, OpenShift Lightspeed and other products, and Exploit Intelligence has no fix planned.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

Fix · CNA filelock (tox-dev) Fixed in 4.2.1
Fix · GHSA-2g95-wg33-c5x2 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-2026-112906
2026-10-21 Affected versions changed · Red Hat
2026-10-21 CVSS score added · Red Hat
2026-10-23 Alias added: GHSA-2g95-wg33-c5x2
2026-10-23 Fix available: PyPI/[email protected] · GHSA-2g95-wg33-c5x2
2026-10-23 CVSS score added · GHSA-2g95-wg33-c5x2
2026-10-23 Weakness changed · GHSA-2g95-wg33-c5x2
2026-10-23 6 new references · GHSA-2g95-wg33-c5x2
2026-10-27 Weakness changed · NVD

References

Other 3

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-2026-76852 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

See all 14 →

Sources

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