All existing Joomla! users MUST UPGRADE to this version, due to several High Level vulnerabilities that affect ALL Previous versions of Joomla!

1.0.10 contains the following important security fixes:

* 03 High Level Security Fixes
* 01 Medium Level Security Fixes
* 05 Low Level security
* 40 General bug fixes

Link: Joomla! - Upgrade to Joomla! 1.0.10 Security Release!