TI-2026-76857 Aliases CVE-2026-112934 GHSA-fj95-fr6c-h845

Unsafe holder record refresh in filelock SoftReadWriteLock

MEDIUM 60CWE-62Published 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: None · Low · 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

filelock for Python, from 4.0.0 before 4.2.1, refreshes SoftReadWriteLock holder records by name. A local user with rename access to the lock directory can replace a record with a named pipe to stall the lock or, under a permissive hard-link policy, link a target file so the lock user writes through it. The weakness is CWE-62, UNIX Hard Link. 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 4.0.0 until 4.2.1, SoftReadWriteLock refreshes holder records by name, allowing another local user with rename access to the lock directory to replace a record with a named pipe and stall the lock, or under a permissive hard-link policy to link a reachable target file and cause the lock user to write through it. This issue is fixed in version 4.2.1.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.00233 14th 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	4.0.0 to before 4.2.1	4.2.1	Patch available	CNA
—	filelock (PyPI)	4.0.0 to before 4.2.1	4.2.1	Patch available	GHSA-fj95-fr6c-h845

filelock Vendortox-dev Affected 4.0.0 to before 4.2.1 Fixed in 4.2.1 Patch available CNA
filelock (PyPI) Vendor— Affected 4.0.0 to before 4.2.1 Fixed in 4.2.1 Patch available GHSA-fj95-fr6c-h845

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:tox-dev:filelock::::::python::*	4.0.0 to before 4.2.1	Vulnerable	tox-dev

cpe:2.3:a:tox-dev:filelock:*:*:*:*:*:python:*:* Versions 4.0.0 to before 4.2.1 Vulnerable ·tox-dev

Remediation

Upgrade the PyPI filelock package to 4.2.1, which fixes this flaw. Red Hat lists no available fix for Ansible Automation Platform 2, 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-fj95-fr6c-h845 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-2026-112934
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-fj95-fr6c-h845
2026-10-28 Fix available: PyPI/[email protected] · GHSA-fj95-fr6c-h845
2026-10-28 CVSS score added · GHSA-fj95-fr6c-h845
2026-10-28 Weakness changed · GHSA-fj95-fr6c-h845
2026-10-28 6 new references · GHSA-fj95-fr6c-h845

References

Exploit 1

https://github.com/tox-dev/filelock/security/advisories/GHSA-fj95-fr6c-h845

Patch 2

Advisory 1

https://nvd.nist.gov/vuln/detail/CVE-2026-112934

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-2026-76852 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

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