    public function validate($string, $config, $context) {
        if ($this->valid_values === false) $this->valid_values = $config->get('Attr.AllowedFrameTargets');
        return parent::validate($string, $config, $context);
    }
The software does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.