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

Severity: high (CVSS 7.3 v4.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-29 · updated 2026-10-02
Weakness: CWE-78

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.

Affected products

Pypi Virtualenv: before 21.7.12; 0.8, 0.8.1, 0.8.2, 0.8.3, 0.8.4, 0.9 (+275) — fixed in 21.7.12
pypa virtualenv: before 21.7.12

How to fix

Upgrade to a fixed version: Pypi Virtualenv 21.7.12. Check the vendor advisory for mitigations.

References

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