pypa virtualenv up to 21.14.3 Bash Activate Script VIRTUALENV_PROMPT os command injection

Summaryinfo

A vulnerability classified as problematic has been found in pypa virtualenv up to 21.14.3. This affects an unknown function of the component Bash Activate Script. The manipulation of the argument VIRTUALENV_PROMPT leads to os command injection. This vulnerability is listed as CVE-2026-113726. The attack must be carried out locally. There is no available exploit. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in pypa virtualenv up to 21.14.3. It has been rated as problematic. This issue affects some unknown processing of the component Bash Activate Script. The manipulation of the argument VIRTUALENV_PROMPT with an unknown input leads to a os command injection vulnerability. Using CWE to declare the problem leads to CWE-78. The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

virtualenv is a tool for creating isolated virtual python environments. Prior to 21.13.0, the bash activate script that zsh also sources leaves the environment name unescaped; from 21.13.0 until 21.14.4, it escapes backslashes, dollar signs, and backticks only when BASH_VERSION is set, so zsh receives the raw value. The script assigns that value to PS1. In zsh with PROMPT_SUBST, an attacker-influenced environment directory, --prompt, or VIRTUALENV_PROMPT value containing command, parameter, or arithmetic expansion syntax can therefore execute commands in the user's shell each time the prompt is drawn. A percent sign is separately interpreted as a zsh prompt escape but does not by itself execute commands. Plain zsh with PROMPT_SUBST disabled and bash are not affected by this mechanism. This issue is fixed in version 21.14.4.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-113726 since 10/20/2026. The exploitation is known to be easy. An attack has to be approached locally. It demands that the victim is doing some kind of user interaction. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1202 for this issue.

Upgrading to version 21.14.4 eliminates this vulnerability.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Vendor

• pypa

Name

• virtualenv

Version

• 21.14.0
• 21.14.1
• 21.14.2
• 21.14.3

Website

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

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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