Upgrade to version 4.6.2 or higher, as it has been reported to fix this vulnerability. An upgrade is required as there are no known workarounds.
Vendor Specific News/Changelog Entry: http://www.tracker.mambo-foundation.org/?do=details&task_id=170
Secunia Advisory ID:25039
Related OSVDB ID: 35540
Bugtraq ID: 23787