The Joomla! team has released a security update [1] for Joomla 1.0.x versions. You can help by downloading the patch or full version [2] and submit any bugs you have encountered.
NOTE: Patch packages for 1.0.14 RC1 only exist going back to Joomla! version 1.0.12. If you need to upgrade from an earlier version you will need to first upgrade to 1.0.13 then upgrade to 1.0.14 RC1
Please do not use this on a production site until a stable release is out
Links:
[1] http://www.joomla.org/content/view/4446/1/
[2] http://joomlacode.org/gf/project/joomla/frs/
[3] http://duvien.com/node/41
[4] http://duvien.com/node/43