---
id: CVE-2026-113726
title: >-
  virtualenv activate runs commands from the environment name in zsh with
  PROMPT_SUBST
summary: >-
  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 si…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H'
cvssSource: cna
cwe:
  - CWE-78
  - CWE-116
vendor: pypa
product: virtualenv
affected:
  - virtualenv < 21.14.4
published: '2026-10-20'
updated: '2026-10-20'
sourceUpdated: '2026-10-20T22:05:24.253Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-113726'
references:
  - url: 'https://github.com/pypa/virtualenv/security/advisories/GHSA-5vjq-rrrf-7h2q'
    label: 'https://github.com/pypa/virtualenv/security/advisories/GHSA-5vjq-rrrf-7h2q'
  - url: >-
      https://github.com/pypa/virtualenv/commit/5b915367da82bd024b2a0d28d2f98007034b4aa2
    label: >-
      https://github.com/pypa/virtualenv/commit/5b915367da82bd024b2a0d28d2f98007034b4aa2
  - url: 'https://github.com/pypa/virtualenv/releases/tag/21.14.4'
    label: 'https://github.com/pypa/virtualenv/releases/tag/21.14.4'
tags:
  - cve.org
ingestedAt: '2026-10-20T22:23:33.689Z'
---

## Overview

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.

## Affected

- `virtualenv < 21.14.4`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.