Nortel VPN Router (aka Contivity) 1000, 2000, 4000, and 5000 before 5_05.149, 5_05.3xx before 5_05.304, and 6.x before 6_05.140 has two template HTML files lacking certain verification tags, which allows remote attackers to access the administration interface and change the device configuration via certain requests.
http://www.vupen.com/english/advisories/2007/1464
http://www.securitytracker.com/id?1017943
http://www.securityfocus.com/bid/23562