Actually I just tried on an app that runs on Gunicorn and does a Popen with shell=True, and it is vulnerable. A simple curl -A '() { :;}; touch /tmp/owned' did

Actually I just tried on an app that runs on Gunicorn and does a Popen with shell=True, and it is vulnerable. A simple curl -A '() { :;}; touch /tmp/owned' did create the file on the server.