source: http://www.securityfocus.com/bid/8734/info

It has been reported that Gamespy 3D IRC client may be prone to a remote buffer overflow vulnerability due to insufficient boundary checking. The issue is reported to present itself when the client attempts to connect to a remote IRC server. During the connection process the client is reported to a send USER and NICK requests to the server. A buffer overflow condition may occur if the server responds with a request that is larger than or equal to 262 bytes.

Successful exploitation of this issue may allow an attacker to execute arbitrary code in the context of the client in order to gain unauthorized access to a vulnerable system.

Gamespy 3D versions 2.63015 and prior have been reported to be prone to this issue, however other versions may be affected as well.

You can use a text file containing a long string and launching netcat in
listening mode:

nc -l -p 6667 -v -v -n < long_string.txt