CVE-2026-102938
virtualenv writes prompt values into pyvenv.cfg without sanitizing line boundaries, allowing configuration injection
Impact
virtualenv is a tool for creating isolated virtual python environments. Prior to 21.7.11, PyEnvCfg.write() writes prompt values verbatim to the line-oriented pyvenv.cfg format while PyEnvCfg._read_values() parses the file with str.splitlines() and accepts the last value for duplicate keys. An attacker who influences --prompt, VIRTUALENV_PROMPT, or configuration input can insert a recognized line boundary and additional keys, including home, causing consumers to use an attacker-selected base interpreter or corrupted environment metadata. The security impact requires prompt input from outside the operator's trust boundary; directly supplied prompt content primarily corrupts the operator's own environment. This issue is fixed in version 21.7.11.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| pip | virtualenv | <= 21.7.10 | 21.7.11 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-9h9j-4vrj-gf7g
- https://github.com/pypa/virtualenv/security/advisories/GHSA-9h9j-4vrj-gf7g
- https://nvd.nist.gov/vuln/detail/CVE-2026-102938
- https://github.com/pypa/virtualenv/pull/3247
- https://github.com/pypa/virtualenv/commit/a30f995461043acb6cacbf3a890951563ccf7140
- https://github.com/pypa/advisory-database/tree/main/vulns/virtualenv/PYSEC-2026-4012.yaml
- https://github.com/pypa/virtualenv/releases/tag/21.7.11
- https://pypi.org/project/virtualenv