High · CVSS 7.8CVE-2026-113726

virtualenv activate runs commands from the environment name in zsh with PROMPT_SUBSTCVE-2026-113726

Answer in brief

CVE-2026-113726 records a High severity (CVSS 7.8) vulnerability in virtualenv activate runs commands from the environment name in zsh with PROMPT_SUBST. The current sources do not mark it as known exploited. The current feed maps pypa/virtualenv (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Oct 20, 2026Updated Oct 20, 2026Source checked Oct 20, 2026First seen by HOL Oct 20, 2026Material review Oct 20, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 7.8
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 7.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps pypa/virtualenv (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
pypa/virtualenvgeneric	<21.14.4	21.14.4

Recommended response

Check inventory. Check lockfiles and deployed manifests for pypa/virtualenv.
Review the reported fix. Update pypa/virtualenv to 21.14.4 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Oct 20, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Oct 20, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Oct 20, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.