Sign in
Deutsch English Español Polski
High

Command injection via --prompt in activate.bat (batch activator)

  • Disclosed: 18.09.2026
  • Updated: 11.10.2026 15:18

BatchActivator.quote() returned its input unchanged, the only activator with no escaping at all. --prompt, the VIRTUALENV_PROMPT environment variable, and the config file all set the prompt, and activate.bat writes it straight into @set "VAR=value". A prompt containing a double quote closes that string early, and whatever follows runs as live cmd.exe syntax. For example, a venv created with --prompt 'x" & calc & "' runs calc the moment someone runs activate.bat.

Anyone who templates a prompt from untrusted input (a CI job using a branch name, a wrapper script deriving an environment name from user input) hands an attacker code execution in the shell of anyone who activates the resulting venv on Windows.

Fixed in 21.7.12 by escaping the characters cmd.exe treats as live syntax inside this construct.

Affected software

Click a technology to see all vulnerabilities affecting it.

PlatformPackageVulnerable versionsFixed in
Python (PyPI) virtualenv < 21.7.12 21.7.12

References

CVSS score -
CVSS 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
Weakness (CWE)
CWE-78
Platform
Python (PyPI)
Package
virtualenv
Disclosed
18.09.2026
Updated
11.10.2026 15:18

Sources and licenses

OSV / GitHub Advisory Database - GHSA-x78j-v8h9-3j2q - CC BY 4.0

OSV / GitHub Advisory Database - PYSEC-2026-4014 - PyPA Advisory Database; CC BY 4.0

Vulnerability history: virtualenv

All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.

Total entries
7
First → latest
12.2011 09.2026
Without a fix
0
Exploited in attacks
0

Severity breakdown

  • High 4
  • Medium 3

Disclosures per year

earlier: 1

  1. virtualenv bash and fish activation scripts execute commands embedded in paths
    High · 7.8 CVE-2026-102925 < 21.7.13 21.7.13
  2. Downloaded seed wheels (pip/setuptools) are not integrity-checked before use
    High CVE-2026-102930 < 21.7.12 21.7.12
  3. Command injection via --prompt in activate.bat (batch activator) this entry
    High CVE-2026-102937 < 21.7.12 21.7.12
  4. virtualenv writes prompt values into pyvenv.cfg without sanitizing line boundaries, allowing configuration injection
    Medium CVE-2026-102938 < 21.7.11 21.7.11
  5. virtualenv Has TOCTOU Vulnerabilities in Directory Creation
    Medium · 4.5 CVE-2026-22702 < 20.36.1 20.36.1
  6. virtualenv allows command injection through activation scripts for a virtual environment
    High · 8.4 CVE-2024-53899 < 20.26.6 20.26.6
  7. virtualenv.py in virtualenv before 1.5 allows local users to overwrite arbitrary files via a symlink attack on a certain file in /tmp/.
    Medium · 6.2 CVE-2011-4617 < 1.5 1.5

Know which vulnerabilities affect your application

With the DockRay integration and software inventory enabled, DockRay checks reported component versions against known vulnerabilities and notifies you about confirmed matches. Coverage depends on the supported technology and available advisory data.

Connect your application
DockRay newsletter

Application security in your inbox

Important vulnerabilities, actionable guidance and practical advice for your applications. Choose your technologies and follow what matters to your project.

  • A daily digest of new vulnerabilities, critical ones included.
  • Notifications about important updates.
  • Practical advice on application security and monitoring.

Leave empty to receive updates for every technology.

Privacy policy

Free to subscribe. Unsubscribe with one click in any email.