Cisco IOS 12.2 12.4 15.0 15.1 15.2 15.3 and 15.4 and IOS XE 2.5.x 2.6.x 3.1.xS through 3.12.xS before 3.12.3S 3.2.xE through 3.7.xE before 3.7.1E 3.3.xSG 3.4.xSG and 3.13.xS before 3.13.2S allow remote attackers to cause a denial of service (device reload) by sending malformed IKEv2 packets over (1) IPv4 or (2) IPv6 aka Bug ID CSCum36951.