CVE-2026-113723: OS Command Injection via Unsafe Prompt Expansion in PyPA virtualenv

Vulnerability ID: CVE-2026-113723
CVSS Score: 7.1
Published: 2026-10-23

A command injection vulnerability in PyPA virtualenv prior to version 21.14.9 allows local attackers to execute arbitrary commands when a user sources a generated shell activation script containing a crafted prompt value.

TL;DR

Unsafe string replacement in virtualenv bash activation scripts allows arbitrary command execution via crafted prompt names during environment activation.

⚠️ Exploit Status: POC

Technical Details

• CWE ID: CWE-78
• CVSS v4.0 Score: 7.1 (High)
• Attack Vector: Local
• EPSS Score: 0.00142 (3.23th percentile)
• CISA KEV: Not Listed
• Exploit Status: Proof of Concept Available
• Impact: Arbitrary Code Execution

Affected Systems

• PyPA virtualenv prior to version 21.14.9
• Linux, macOS, and Unix systems sourcing Bash/Zsh activation scripts
• virtualenv: < 21.14.9 (Fixed in: 21.14.9)

Code Analysis

Commit: 5f48d71

Fix PS1 prompt escaping and evaluation logic in bash activation script

Exploit Details

• GitHub Security Advisory: Advisory detailing proof-of-concept command injection via crafted prompt strings.

Mitigation Strategies

• Upgrade virtualenv to version 21.14.9 or higher.
• Regenerate pre-existing virtual environments created with vulnerable virtualenv releases.
• Set VIRTUAL_ENV_DISABLE_PROMPT=1 in shell environments to skip PS1 modifications.

Remediation Steps:

1. Execute 'pip install --upgrade virtualenv>=21.14.9' in the environment build pipeline.
2. Remove old virtual environment directories using 'rm -rf .venv'.
3. Re-create virtual environments using the updated virtualenv package.
4. Verify that bin/activate contains literal variable references for PS1 assignments.

References

• GitHub Security Advisory GHSA-6w3r-xr62-4xcp
• Fix Commit 5f48d711731311428aebfae61d46957762155b22
• GitHub Pull Request #3418
• virtualenv Release 21.14.9
• NIST NVD CVE-2026-113723 Record
• CVE Program Record

Read the full report for CVE-2026-113723 on our website for more details including interactive diagrams and full exploit analysis.