pypa virtualenv up to 21.7.10 Configuration Parsing pyvenv.cfg PyEnvCfg._read_values --prompt/VIRTUALENV_PROMPT/configuration input input validation

Summaryinfo

A vulnerability identified as problematic has been detected in pypa virtualenv up to 21.7.10. The affected element is the function PyEnvCfg._read_values of the file pyvenv.cfg of the component Configuration Parsing. The manipulation of the argument --prompt/VIRTUALENV_PROMPT/configuration input leads to input validation. This vulnerability is documented as CVE-2026-102938. The attack can be initiated remotely. There is not any exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in pypa virtualenv up to 21.7.10 and classified as problematic. This issue affects the function PyEnvCfg._read_values of the file pyvenv.cfg of the component Configuration Parsing. The manipulation of the argument --prompt/VIRTUALENV_PROMPT/configuration input with an unknown input leads to a input validation vulnerability. Using CWE to declare the problem leads to CWE-20. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. Impacted is integrity, and availability. The summary by CVE is:

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.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-102938 since 09/29/2026. The exploitation is known to be easy. The attack may be initiated remotely. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 21.7.11 eliminates this vulnerability.

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Productinfo

Vendor

• pypa

Name

• virtualenv

Version

• 21.7.0
• 21.7.1
• 21.7.2
• 21.7.3
• 21.7.4
• 21.7.5
• 21.7.6
• 21.7.7
• 21.7.8
• 21.7.9
• 21.7.10

Website

• Product: https://github.com/pypa/virtualenv/

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