[Plugin: Capability Manager] How can I stop lower-level roles from creating a new ADMIN user?

This have to be with the way WordPress manages Roles and Capabilities. If a user has the capability to create new users, can assign to them any role. I know this is a security issue, and will check with other developers if there is a way to manage it.

I have the same need and I am searching for plugin. I am a newbie for WP and cannot create a plugin yet but I have found the following function in wp-admin/includes/user.php. It suggests that since 2.8 users could have limited rights to assign roles.

/**
* Fetch a filtered list of user roles that the current user is
* allowed to edit.
*
* Simple function who’s main purpose is to allow filtering of the
* list of roles in the $wp_roles object so that plugins can remove
* innappropriate ones depending on the situation or user making edits.
* Specifically because without filtering anyone with the edit_users
* capability can edit others to be administrators, even if they are
* only editors or authors. This filter allows admins to delegate
* user management.
*
* @since 2.8
*
* @return unknown
*/
function get_editable_roles()
…