CVE-2026-113715: virtualenv: Venv configuration readback can reinterpret path boundaries

Severity: low (CVSS 2.0 v4.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-20 · updated 2026-10-23
Weakness: CWE-93

Description

virtualenv is a tool for creating isolated virtual python environments. Prior to 21.14.9, the stdlib venv creator reads generated pyvenv.cfg with str.splitlines() and merges parsed keys over virtualenv's selected configuration. An untrusted caller who influences the destination pathname can include a line-boundary character such as U+2028 to inject keys including home and include-system-site-packages, causing path data to change configuration structure before final output. Setting include-system-site-packages to true weakens environment isolation, while an altered home can change which standard-library files the interpreter loads if the attacker also controls that location. The builtin creator does not use this readback path. This issue is fixed in version 21.14.9.

Affected products

Pypi Virtualenv: before 21.14.9; 0.8, 0.8.1, 0.8.2, 0.8.3, 0.8.4, 0.9 (+298) — fixed in 21.14.9
pypa virtualenv: before 21.14.9

How to fix

Upgrade to a fixed version: Pypi Virtualenv 21.14.9. Check the vendor advisory for mitigations.

References

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