base/logging.c in Nagios Core before 4.2.4 allows local users with access to an account in the nagios group to gain root privileges via a symlink attack on the log file. NOTE: this can be leveraged by remote attackers using CVE-2016-9565.
https://www.nagios.org/projects/nagios-core/history/4x/
https://www.exploit-db.com/exploits/40921/
https://security.gentoo.org/glsa/201710-20
https://security.gentoo.org/glsa/201702-26
https://security.gentoo.org/glsa/201612-51
https://lists.debian.org/debian-lts-announce/2018/12/msg00014.html
https://github.com/NagiosEnterprises/nagioscore/commit/c29557dec91eba2306f5fb11b8da4474ba63f8c4
https://bugzilla.redhat.com/show_bug.cgi?id=1402869
http://www.securitytracker.com/id/1037487
http://www.securityfocus.com/bid/94919
http://seclists.org/fulldisclosure/2016/Dec/58
http://rhn.redhat.com/errata/RHSA-2017-0259.html
http://rhn.redhat.com/errata/RHSA-2017-0258.html
http://rhn.redhat.com/errata/RHSA-2017-0214.html
http://rhn.redhat.com/errata/RHSA-2017-0213.html