Unspecified vulnerability in Cisco IOS 12.2 through 12.4, when certificate-based authentication is enabled for IKE, allows remote attackers to cause a denial of service (Phase 1 SA exhaustion) via crafted requests, aka Bug IDs CSCsy07555 and CSCee72997.
http://www.vupen.com/english/advisories/2009/2759
http://www.cisco.com/en/US/products/products_security_advisory09186a0080af8117.shtml
http://tools.cisco.com/security/center/viewAlert.x?alertId=18887