Quartz Composer Screen Saver in Mac OS X 10.4.2 allows local users to access links from the RSS Visualizer even when a password is required.
http://securitytracker.com/id?1014705
http://lists.apple.com/archives/security-announce/2005/Aug/msg00000.html
http://lists.apple.com/archives/security-announce/2005//Aug/msg00001.html