Cisco IOS 12.4 and 15.0 through 15.6 and IOS XE 3.1 through 3.18 and 16.1 allow remote attackers to cause a denial of service (memory consumption or device reload) via fragmented IKEv1 packets, aka Bug ID CSCuy47382.
http://www.securitytracker.com/id/1036914
http://www.securityfocus.com/bid/93195
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20160928-ios-ikev1