TI-2026-76855 Aliases CVE-2026-112914 GHSA-crv4-6mhj-j5jh

Link following in filelock SoftFileLock lets local users link files

LOW 23CWE-363Published 2026-10-20 · Updated 2026-10-21

Key facts

Attack vector: Local
Privileges required: Low
User interaction: None
Attack complexity: High
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

The filelock Python library from 4.1.0 before 4.2.1 has a link following flaw in SoftFileLock stale marker restoration (CWE-59). A local user with rename access to a non-sticky lock directory can swap in a symbolic link, causing the lock user to hard-link one of its files into that directory on runtimes that follow the link. 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 can restore a stale marker by name after moving it aside, allowing another local user with rename access in a non-sticky lock directory to swap in a symbolic link and, on a runtime that follows the link and a same-filesystem target, make the lock user hard-link one of its files into the lock directory. This issue is fixed in version 4.2.1.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00161 5th 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: None
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-crv4-6mhj-j5jh

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-crv4-6mhj-j5jh

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 filelock to version 4.2.1, which fixes this issue. Red Hat rates the flaw Moderate and lists fifteen products as affected without a fix, including Red Hat OpenShift Container Platform 4 and Red Hat Ansible Automation Platform 2, with no fix available for most of them and no fix planned for Exploit Intelligence.

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-crv4-6mhj-j5jh 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-2026-112914
2026-10-21 Affected versions changed · Red Hat
2026-10-21 CVSS score added · Red Hat
2026-10-21 CISA SSVC decision points changed
2026-10-21 Weakness changed · NVD
2026-10-23 Alias added: GHSA-crv4-6mhj-j5jh
2026-10-23 Fix available: PyPI/[email protected] · GHSA-crv4-6mhj-j5jh
2026-10-23 CVSS score added · GHSA-crv4-6mhj-j5jh
2026-10-23 Weakness changed · GHSA-crv4-6mhj-j5jh
2026-10-23 6 new references · GHSA-crv4-6mhj-j5jh

References

Exploit 1

https://github.com/tox-dev/filelock/security/advisories/GHSA-crv4-6mhj-j5jh

Patch 2

Advisory 1

https://nvd.nist.gov/vuln/detail/CVE-2026-112914

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-2026-76852 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

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