A security release is available for Joomla! 1.5, it's the version 1.5.23, called "Senu takaa ama baji". This new release corrects  an information disclosure vulnerability found in the version 1.5.22 and all previous 1.5 versions.

This is a low priority release, and you're strongly encouraged to upgrade your website as soon as possible. Here it is all the necessary links :

• Download Joomla 1.5.23 (full package),
• Download an upgrade package,
• More details about ths release.