A security issue was fixed in the Apache HTTP Server.
It was discovered that the Apache HTTP Server would set the HTTP_PROXY environment variable based on the contents of the Proxy header from HTTP requests. A remote attacker could possibly use this issue in combination with CGI scripts that honour the HTTP_PROXY variable to redirect outgoing HTTP requests.
18 July 2016
A security issue affects these releases of Ubuntu and its derivatives:
A security issue was fixed in the Apache HTTP Server.
It was discovered that the Apache HTTP Server would set the HTTP_PROXY environment variable based on the contents of the Proxy header from HTTP requests. A remote attacker could possibly use this issue in combination with CGI scripts that honour the HTTP_PROXY variable to redirect outgoing HTTP requests.
The problem can be corrected by updating your system to the following package versions:
To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.
In general, a standard system update will make all the necessary changes.