Joomla! Core is prone to a security bypass vulnerability. Exploiting this issue may allow attackers to perform otherwise restricted actions and subsequently retrieve password reset tokens from the database through an already existing SQL injection vector. Joomla! Core versions 1.5.x ranging from 1.5.0 and up to and including 1.5.15 are vulnerable.
Update to Joomla! Core version 1.5.16 or latest