    function action_default_save_licence_key() {
        $license = W3_Request::get_string('license_key');
        try {
            $old_config = new W3_Config();

            $this->_config->set('plugin.license_key', $license);
            $this->_config->save();

            w3_instance('W3_Licensing')->possible_state_change($this->_config,
+                $old_config);
        } catch(Exception $ex){
            echo json_encode(array('result' => 'failed'));
            exit;
        }
        echo json_encode(array('result' => 'success'));
        exit;
    }
The web application does not, or can not, sufficiently verify whether a well-formed, valid, consistent request was intentionally provided by the user who submitted the request.