Linux Security Resources
Kyle Amon,  Page 26 

Debian
http://www.debian.org/security/

RedHat
http://www.redhat.com/corp/support/errata/rh-errata.html

SuSE
http://www.suse.de/de/support/security/ 

Slackware
slackware-security
slackware-security-digest
majordomo@slackware.com

Caldera
http://www.calderasystems.com/support/security/

BackWatcher, Inc.
http://www.backwatcher.com/ 
http://www.backwatcher.org/ 
http://www.backwatcher.net/