CVE-2016-9566: base/logging.c in Nagios Core before 4.2.4 allows local users with access to an account in the nagios group...

Security readout for executives and security teams

CVE-2016-9566 is a Nagios Core privilege-escalation flaw fixed before version 4.2.4. A user with access to an account in the nagios group could abuse log-file handling to gain root privileges. Sources also note it can be chained with CVE-2016-9565 by remote attackers. Exposure is most likely on systems running Nagios Core before 4.2.4 where users or services have access to an account in the nagios group. Remote exposure depends on whether CVE-2016-9565 is also exploitable in the environment. Prioritize remediation on monitoring servers because compromise can grant root access on infrastructure that often has broad operational visibility. Treat internet-adjacent or multi-user Nagios deployments as higher urgency, especially if CVE-2016-9565 may also be present. Mitigation focus: Upgrade Nagios Core to version 4.2.4 or a vendor-fixed package.; Review Gentoo, Red Hat, Debian, or upstream Nagios advisories for platform-specific fixes.; Restrict membership and interactive access to accounts in the nagios group..

Prepared

Jun 13, 2026, 13:16 UTC (UTC+00:00)

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.