To stay up-to-date with the security fixes you should subscribe to receive GLSAs and apply GLSA instructions whenever you have an affected package installed.
http://www.gentoo.org/security/en/index.xml

Abstract . This document outlines a method for receiving regular notifications via email of Gentoo Linux Security Advisories (GLSA) related to the specific packages you have ...
http://gentoo-wiki.com/SECURITY_Getting_GLSAs_by_Email

GLSA 200802-12 (Normal): xine-lib - 27/02/2008 00:00 GMT xine-lib: User-assisted execution of arbitrary code
http://gentoo-portage.com/GLSA