qh_echo in Nagios Core 4.4.1 and earlier is prone to a NULL pointer dereference vulnerability, which allows attackers to cause a local denial-of-service condition by sending a crafted payload to the listening UNIX socket.
lists.opensuse.org/opensuse-security-announce/2020-04/msg00014.html
lists.opensuse.org/opensuse-security-announce/2020-04/msg00022.html
gist.github.com/fakhrizulkifli/87cf1c1ad403b4d40a86d90c9c9bf7ab
knowledge.opsview.com/v5.3/docs/whats-new
knowledge.opsview.com/v5.4/docs/whats-new
www.exploit-db.com/exploits/45082/