CVE-2026-112912

filelock: Symlink swap during SoftFileLock's writability check leaks whether a path exists and is writable by the lock taker

Published Oct 20, 2026 CVSS 3.1 · 2.5 Low EPSS < 1% KEV · Not listed
Description
filelock is a platform-independent file lock for Python. From 3.32.6 until 4.2.1, SoftFileLock can follow a swapped symbolic link during the conditional os.access writability check for a node without its owner-write bit, allowing another local user on a platform and directory configuration that follows the link to infer whether a chosen path exists and is writable from the observable acquisition result. This issue is fixed in version 4.2.1.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-9j6q-wvj5-jgjg filelock: Symlink swap during SoftFileLock's writability check leaks whether a path exists and is writable by the lock taker
History
Type Values Removed Values Added
CPEs cpe:2.3:a:tox-dev:filelock:*:*:*:*:*:python:*:*
Type Values Removed Values Added
First Time appeared Tox-dev
Tox-dev filelock
Vendors & Products Tox-dev
Tox-dev filelock
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description filelock is a platform-independent file lock for Python. From 3.32.6 until 4.2.1, SoftFileLock can follow a swapped symbolic link during the conditional os.access writability check for a node without its owner-write bit, allowing another local user on a platform and directory configuration that follows the link to infer whether a chosen path exists and is writable from the observable acquisition result. This issue is fixed in version 4.2.1.
Title filelock: Symlink swap during SoftFileLock's writability check leaks whether a path exists and is writable by the lock taker
Weaknesses CWE-59
References
Metrics cvssV3_1

{'score': 2.5, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Oct 20, 2026, 3:37 PM
Reserved
Oct 19, 2026, 8:16 PM
Status
Analyzed
Published
Oct 20, 2026, 3:17 PM
Modified
Oct 21, 2026, 9:18 PM
Severity
Low
Public date
Oct 20, 2026, 2:23 PM