The IKEv1 implementation in Cisco IOS 12.2 through 12.4 and 15.0 through 15.2 and IOS XE 2.1.x through 2.6.x and 3.1.xS through 3.4.xS before 3.4.2S, 3.5.xS before 3.5.1S, and 3.2.xSG before 3.2.2SG allows remote attackers to cause a denial of service (device reload) by sending IKE UDP packets over (1) IPv4 or (2) IPv6, aka Bug ID CSCts38429.