    protected function driverRead(CacheItemInterface $item)
    {
        $this->driverConnect();
        // return null if no caching
        // return value if in caching
        $keyword = self::PREFIX . $item->getKey();
        $x = isset($_COOKIE[ $keyword ]) ? $this->decode(json_decode($_COOKIE[ $keyword ], true)) : false;

        if ($x == false) {
            return null;
        } else {
            if (!is_scalar($this->driverUnwrapData($x)) && !is_null($this->driverUnwrapData($x))) {
                throw new phpFastCacheDriverException('Hacking attempt: The decoding returned a non-scalar value, Cookie driver does not allow this.');
            }

            return $x;
        }
    }
The application deserializes untrusted data without sufficiently verifying that the resulting data will be valid.