CVE-2026-102938

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 operators trust boundary; directly supplied prompt content primarily corrupts the operators own environment. This issue is fixed in version 21.7.11.

Weakness

The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes CRLF sequences from inputs.

Affected Software

Potential Mitigations

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/15.html
• https://cwe.mitre.org/data/definitions/81.html

References

• https://github.com/pypa/virtualenv/commit/a30f995461043acb6cacbf3a890951563ccf7140
• https://github.com/pypa/virtualenv/pull/3247
• https://github.com/pypa/virtualenv/releases/tag/21.7.11
• https://github.com/pypa/virtualenv/security/advisories/GHSA-9h9j-4vrj-gf7g