---
id: CVE-2026-112914
title: >-
  filelock: SoftFileLock stale-break restore follows a swapped-in symbolic link
  and hard-links a file of the user running the lock into the lock directory
summary: >-
  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…
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:N'
cvssSource: cna
cwe:
  - CWE-363
vendor: tox-dev
product: filelock
affected:
  - 'filelock >= 4.1.0, < 4.2.1'
published: '2026-10-20'
updated: '2026-10-20'
sourceUpdated: '2026-10-20T14:26:18.813Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-112914'
references:
  - url: >-
      https://github.com/tox-dev/filelock/security/advisories/GHSA-crv4-6mhj-j5jh
    label: >-
      https://github.com/tox-dev/filelock/security/advisories/GHSA-crv4-6mhj-j5jh
  - url: 'https://github.com/tox-dev/filelock/pull/843'
    label: 'https://github.com/tox-dev/filelock/pull/843'
  - url: >-
      https://github.com/tox-dev/filelock/commit/740ff666b62a88496c8d7394e4e6230605e4d62b
    label: >-
      https://github.com/tox-dev/filelock/commit/740ff666b62a88496c8d7394e4e6230605e4d62b
  - url: 'https://github.com/tox-dev/filelock/releases/tag/4.2.1'
    label: 'https://github.com/tox-dev/filelock/releases/tag/4.2.1'
tags:
  - cve.org
ingestedAt: '2026-10-20T15:09:24.124Z'
---

## Overview

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.

## Affected

- `filelock >= 4.1.0, < 4.2.1`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.