Buffer overflow in the UGameEngine::UpdateConnectingMessage function in the Unreal engine 1, 2, and 2.5, as used in multiple games including Unreal Tournament 2004, Unreal tournament 2003, Postal 2, Raven Shield, and SWAT4, when downloads are enabled, allows remote attackers to execute arbitrary code via a long LEVEL field in a WELCOME response to a download request.