Stack-based buffer overflow in the ClientConnection::NegotiateProtocolVersion function in vncviewer/ClientConnection.cpp in vncviewer for UltraVNC 1.0.2 and 1.0.4 before 01252008, when in LISTENING mode or when using the DSM plugin, allows remote attackers to execute arbitrary code or cause a denial of service (crash) via a modified size value.
http://www.vupen.com/english/advisories/2008/0392
http://www.securitytracker.com/id?1019293
http://www.kb.cert.org/vuls/id/721460
http://www.exploit-db.com/exploits/18666
http://sourceforge.net/project/shownotes.php?release_id=571174&group_id=63887