CVE-2026-112909

What it is

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.

At a glance

Exploitability

Can be exploited locally on the machine with a low-privilege account. High risk of data tampering.

Exploit odds

0.2% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-10-19 20:16 UTC ReservedThe CVE id was reserved by its CNA
2. 2026-10-20 15:17 UTC PublishedDisclosed publicly on CVE.org and NVD
3. 2026-10-27 21:04 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.2% in the next 30 days (EPSS).
• Severity: 6.1 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-10-20 15:17 UTC

Last modified

2026-10-27 21:04 UTC

Exploit probability

0.2% · EPSS, next 30 days

Weakness

CWE-706

Record status

Analyzed

Affected

• tox-dev Filelock < 4.2.1

Attack profile CVSS 3.1 · 6.1

Attack vector

Local

Complexity

Low

Privileges needed

Low

User interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

High

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-112909.md and follow it. Check whether this project is affected by CVE-2026-112909. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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