In Wireshark 2.6.0 to 2.6.5 and 2.4.0 to 2.4.11, the ISAKMP dissector could crash. This was addressed in epan/dissectors/packet-isakmp.c by properly handling the case of a missing decryption data block. https://nvd.nist.gov/vuln/detail/CVE-2019-5719