The dissect_isakmp function in epan/dissectors/packet-isakmp.c in the ISAKMP dissector in Wireshark 1.6.x before 1.6.12 and 1.8.x before 1.8.4 uses an incorrect data structure to determine IKEv2 decryption parameters, which allows remote attackers to cause a denial of service (application crash) via a malformed packet.