Nagios is an open source host, service and network monitoring program.
A vulnerability in Nagios was discovered due to the improper handling of configuration files which can be owned by a non-root user.
A local attacker can escalate privileges to root by leveraging access to a non-root owned configuration file.
There is no known workaround at this time.
All Nagios users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=net-analyzer/nagios-core-4.3.4"