BEA WebLogic Server 6.1 through 6.1 SP7, 7.0 through 7.0 SP6, 8.1 through 8.1 SP5, and 9.0 allows remote attackers to cause a denial of service (server hang) via certain requests that cause muxer threads to block when processing error pages.
http://www.vupen.com/english/advisories/2007/0213
http://www.securityfocus.com/bid/22082
http://securitytracker.com/id?1017525