The HTTPOXY vulnerability that has been found recently is a vulnerability that affects web applications that run in cgi or cgi-like environments. This is not a vulnerability in ISPConfig itself but it affects software that is used on most ISPConfig servers, so it is likely that your server is affected by this issue.
We published a tutorial at Howtoforge that shows the steps to protect your server.
https://www.howtoforge.com/tutorial/httpoxy-protect-your-server/
