htp_parse_authorization_digest in htp_parsers.c in LibHTP 0.5.26 allows remote attackers to cause a heap-based buffer over-read via an authorization digest header.
https://suricata-ids.org/2018/07/18/suricata-4-0-5-available/
https://lists.debian.org/debian-lts-announce/2019/04/msg00010.html