components/com_user/models/reset.php in Joomla! 1.5 through 1.5.5 does not properly validate reset tokens, which allows remote attackers to reset the "first enabled user (lowest id)" password, typically for the administrator.
Category : Permissions, Privileges, and Access Controls Weaknesses in this category are related to the management of permissions, privileges, and other security features that are used to perform access control.