From what I can tell this port has mulitple CVEs unpatched and isn't support by upstream. What are the plans for this port? https://nvd.nist.gov/vuln/search/results?form_type=Advanced&results_type=overview&isCpeNameSearch=true&seach_type=all&query=cpe:2.3:a:nagios:nagios:3.5.1:*:*:*:*:*:*:*
None of them affect production systems, because they are in very specific configs.
net-mgmt/nagios4 4.5.9: https://github.com/NagiosEnterprises/nagioscore/blob/nagios-4.5.9/Changelog