Vulnerability · Published Oct 20, 2026 · Assigned by GitHub_M

CVE-2026-113721virtualenv: Generated files can follow existing destination links

Medium 4.5

In plain English

A medium-severity security flaw in virtualenv from pypa. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 4% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)4.5Medium

Exploit odds (30 days)0.1%top 96.3% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

virtualenv 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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:12	python-virtualenv	no fix listed	DEBIAN-CVE-2026-113721
Debian:13	python-virtualenv	no fix listed	DEBIAN-CVE-2026-113721
Debian:14	python-virtualenv	no fix listed	DEBIAN-CVE-2026-113721
PyPI	virtualenv	21.14.9	GHSA-558c-9hv2-4prj
Ubuntu:26.04:LTS	python-virtualenv	no fix listed	UBUNTU-CVE-2026-113721
Ubuntu:26.10	python-virtualenv	no fix listed	UBUNTU-CVE-2026-113721

Affected products (as reported)

Vendor	Product	Versions
pypa	virtualenv	< 21.14.9

Weakness: CWE-59 · Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L

References

https://github.com/pypa/virtualenv/security/advisories/GHSA-558c-9hv2-4prj x_refsource_CONFIRM
https://github.com/pypa/virtualenv/pull/3431 x_refsource_MISC
https://github.com/pypa/virtualenv/commit/d25f28699eefb1fc34a251e5adf2b5de844c36cd x_refsource_MISC
https://github.com/pypa/virtualenv/releases/tag/21.14.9 x_refsource_MISC