The Joomla! Community announced the release of Joomla! 1.5.1 [Seenu], which fixes a high priority security vulnerability.

It is strongly recommended that all Joomla! 1.5 users upgrade to Joomla! 1.5.1, especially if the XML-RPC system is in use. Other fixes:

• Fixed XML-RPC/Blogger security issue.
• Fix to sef issues including creation of optional livesite parameter if needed which will also allow reverse proxy.
• Change to mass mail so that blind carbon can be used, protecting email addresses of your users.
• Fix to date function that was causing an error in the end publication date for some systems.
• Fixed UTF 8 database detection.
• Addressed a number of internationalization issues.
• Fixes to a number of minor issues 

Link | Release Notes - Download J! 1.5.1