A vulnerability was found in Nagios 4.2.4, and earlier, which allows local users to gain root privileges via a hard link attack on the Nagios init script file, related to CVE-2016-8641.
This flaw, and others like it, are mitigated by enabling hardlink and symlink protections. These protections are enabled by default in Red Hat Enterprise Linux 7 and this vulnerability will only be exploitable if disabled.
Ensure the following protections are enabled:
sysctl -w fs.protected_hardlinks=1
sysctl -w fs.protected_symlinks=1