virtualenv: Generated files can follow existing destination links

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-113721
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-20 20:17:18 UTC
Updated2026-10-20 20:17:18 UTC
Descriptionvirtualenv is a tool for creating isolated virtual python environments. Prior to 21.14.9, ViaTemplateActivator._generate() removes an existing output only when Path.exists() is true, allowing a dangling symlink to survive and redirect generated activation content, while PyEnvCfg.write() opens pyvenv.cfg without first replacing an existing symbolic or hard link. Another local account that prepares final entries inside the destination can therefore cause environment creation to create or overwrite files outside the requested tree with constrained virtualenv-generated content and the invoking user's permissions. The destination parent must remain controlled by the environment owner during creation; concurrent parent-directory replacement is a separate concern. This issue is fixed in version 21.14.9.

Risk And Classification

Primary CVSS: v3.1 4.5 MEDIUM from [email protected]

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

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

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary4.5MEDIUMCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L
3.1CNADECLARED4.5MEDIUMCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L

CVSS v3.1 Breakdown

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

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Pypa Virtualenv affected < 21.14.9 Not specified

References

ReferenceSourceLinkTags
github.com/pypa/virtualenv/security/advisories/GHSA-558c-9hv2-4prj [email protected] github.com
github.com/pypa/virtualenv/releases/tag/21.14.9 [email protected] github.com
github.com/pypa/virtualenv/commit/d25f28699eefb1fc34a251e5adf2b5de844c36cd [email protected] github.com
github.com/pypa/virtualenv/pull/3431 [email protected] github.com
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