Cisco IOS XE 3.1 through 3.17 and 16.1 on 64-bit platforms allows remote attackers to cause a denial of service (data-structure corruption and device reload) via fragmented IPv4 packets, aka Bug ID CSCux66005.
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.