New versions of both the Nagios 1.x and 2.x code branches have been released and contain a fix for another content length (buffer) overflow that could affect the CGIs. Nagios 2.3.1 and (for people running 1.x versions) 1.4.1 can be downloaded here. The Changelog for both releases can be found here. Thanks to Sean Finney and the Debian folks for this patch.
Nagios Update: XI 5.6.6
Nagios XI update 5.6.6 is now released! This update resolves a number of minor bugs and one security vulnerability fix. This version also includes improvements