If you create a custom role using the role manager, and let that role edit options for any reasons (e.g. you want to set up some kind of demo site), then users with that role can open registrations, and assign administrator as the default role, then let themselves in as administrator.
Fix:
function default_role($o)
{
if ( $o == 'administrator' && get_option('users_can_register') )
{
global $wp_roles;
foreach ( $wp_roles->role_names as $role => $name )
{
if ( $role != 'administrator' )
{
$o = $role;
add_action('shutdown', create_function('', "update_option('default_role', '$role');"));
break;
}
}
}
return $o;
} # default_role()
add_filter('option_default_role', 'default_role');
