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[ CVE-2026-113726 · Published 20 Oct 2026 ]

virtualenv activate runs commands from the environment name in zsh with PROMPT_SUBST

CVSS 7.8 EPSS <1%Fix available

[ Description ]Official description

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.

[ Fixes ]Fixes and patches

  • virtualenv 21.14.4Fixed version · GitHub Advisories · pip package virtualenv: upgrade to 21.14.4 or later (affected <= 21.14.3)

[ Packages ]Affected open-source packages

[ References ]References