Please follow the below link in order to read the entire security bulletin covering all 11 extensions.
TYPO3-20080919-1: Collective Security Bulletin covering issues in 11 third party extensions:
typo3.org/teams/security/security-bulletins/typo3-20080919-1/
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.pdf
Make sure you are subscribed to the TYPO3 Announce List:
lists.netfielders.de/cgi-bin/mailman/listinfo/typo3-announce
See all TYPO3 security bulletins: