In Wireshark 2.6.0, 2.4.0 to 2.4.6, and 2.2.0 to 2.2.14, the Q.931 dissector could crash. This was addressed in epan/dissectors/packet-q931.c by avoiding a use-after-free after a malformed packet prevented certain cleanup.
https://www.wireshark.org/security/wnpa-sec-2018-31.html
https://www.debian.org/security/2018/dsa-4217
https://lists.debian.org/debian-lts-announce/2018/05/msg00019.html
https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=14689
http://www.securitytracker.com/id/1041036
http://www.securityfocus.com/bid/104308
http://lists.opensuse.org/opensuse-security-announce/2020-03/msg00027.html