Zendframework Remote Address Spoofing Vector in `Zend\Http\PhpEnvironment\RemoteAddress`

The Zend\Http\PhpEnvironment\RemoteAddress class provides features around detecting the internet protocol (IP) address for an incoming proxied request via the X-Forwarded-For header, taking into account a provided list of trusted proxy server IPs. Prior to 2.2.5, the class was not taking into account whether or not the IP address contained in PHP’s $_SERVER['REMOTE_ADDR'] was in the trusted proxy server list.

The IETF draft specification indicates that if $_SERVER['REMOTE_ADDR'] is not a trusted proxy, it must be considered the originating IP address, and the value of X-Forwarded-For must be disregarded.