For further information, please read the following bulletins:
TYPO3 Security Bulletin TYPO3-20081110-1: Cross-Site Scripting vulnerability in extension phpMyAdmin (phpmyadmin):
http://typo3.org/teams/security/security-bulletins/typo3-20081110-1/
TYPO3 Collective Security Bulletin TYPO3-20081110-2: Several vulnerabilities in third party extensions:
http://typo3.org/teams/security/security-bulletins/typo3-20081110-2/
In general the TYPO3 Security Team recommends you to read the following pages:
The TYPO3 Security Cookbook:
http://typo3.org/fileadmin/security-team/typo3_security_cookbook_v-0.5.pdf
Make sure you are subscribed to the TYPO3 Announce List:
http://lists.netfielders.de/cgi-bin/mailman/listinfo/typo3-announce
See all TYPO3 security bulletins:
http://typo3.org/teams/security/security-bulletins/