The multiplayer menu in OpenTTD 0.4.7 allows remote attackers to cause a denial of service via a UDP packet with an incorrect size, which causes the client to return to the main menu.
https://exchange.xforce.ibmcloud.com/vulnerabilities/26004
http://www.vupen.com/english/advisories/2006/1480
http://www.securityfocus.com/bid/17661
http://www.securityfocus.com/archive/1/431871/100/0/threaded
http://security.gentoo.org/glsa/glsa-200609-03.xml