source: http://www.securityfocus.com/bid/41352/info

Freeciv is prone to multiple remote denial-of-service vulnerabilities because the application fails to properly handle specially crafted network packets.

An attacker can exploit these issues to cause the applications to become unresponsive or to crash the affected game servers, denying service to legitimate users.

Freeciv 2.2.1 is vulnerable; other versions may also be affected. 

http://www.exploit-db.com/sploits/34249.zip