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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-112912
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-20 15:17:15 UTC
Updated2026-10-20 19:48:50 UTC
Descriptionfilelock 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.

Risk And Classification

Primary CVSS: v3.1 2.5 LOW from [email protected]

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N

Problem Types: CWE-59 | CWE-59 CWE-59: Improper Link Resolution Before File Access ('Link Following')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary2.5LOWCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N
3.1CNADECLARED2.5LOWCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Tox-dev Filelock affected >= 3.32.6, < 4.2.1 Not specified

References

ReferenceSourceLinkTags
github.com/tox-dev/filelock/releases/tag/4.2.1 [email protected] github.com
github.com/tox-dev/filelock/security/advisories/GHSA-9j6q-wvj5-jgjg 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
github.com/tox-dev/filelock/commit/e1e825b1992f69fb6b346dc395d5ae4893536c0a [email protected] github.com
github.com/tox-dev/filelock/pull/835 [email protected] github.com
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