Protect your server from HTTPOXY
This post is from 2016. Versions, commands and links in it may be outdated. The current release is ISPConfig 3.3.2p1.
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/