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BIT-virtualenv-2026-113720 — virtualenv: Seeded files retain permissions from an older cache

Affected: Bitnami: virtualenv

virtualenv is a tool for creating isolated virtual python environments. Prior to 21.14.9, the app-data copy seeder uses shutil.copy() to copy cached package files into later environments, causing cached source modes to override the current run's umask. A cache populated under a permissive umask can therefore produce files writable by another local account in a later traversable environment, allowing package code such as pip/__init__.py to be modified and executed by the environment owner. The attacker cannot force the earlier umask, and a private destination parent prevents access. This issue is fixed in version 21.14.9.

CVE-2026-113720 — virtualenv: Seeded files retain permissions from an older cache

Affected: pypa virtualenv

GHSA-fc2g-4w5p-6whm — virtualenv: Seeded files retain permissions from an older cache

Affected: PyPI: virtualenv

## Summary

The app-data copy seeder uses shutil.copy, which preserves cached file modes independently of the current umask. A cache populated under permissive permissions can therefore produce files with wider access in later environments.

Anthropic's OSS Scanner reported this as `ANT-2026-487MH6OW` in `virtualenv-20261015-005`, received on 15 October 2026.

## Affected area

Permissions of files copied from app-data into a new environment.

## Attacker-controlled input

The cache must contain files created with broader permissions than the current environment creator intends. Another account must also be able to traverse the new environment and reach those files. A private parent directory prevents that access. No control of a private live cache is assumed.

## Affected code

The relevant 21.14.8 source is in [copy helpers](https://github.com/pypa/virtualenv/blob/a795ab116356afde11039cf2763d77e8a06da738/src/virtualenv/util/path/_sync.py).

## Mechanism

The default app-data seeder extracts a wheel into a reusable cache and copies its files into later environments with `shutil.copy()`. That function applies the cached source mode to each destination file after creating it, overriding the current run's umask. If the cache image was built under umask `000`, a later environment created under umask `022` can receive mode-`0666` pip files. The cache may be private while the new environment is reachable by other local accounts.

## Reproduction and evidence

The scanner created…