    public function isOld($key, $config) {
        if (substr_count($key, ',') < 2) return true;
        list($version, $hash, $revision) = explode(',', $key, 3);
        $compare = version_compare($version, $config->version);
        // version mismatch, is always old
        if ($compare != 0) return true;
        // versions match, ids match, check revision number
        if (
            $hash == $config->getBatchSerial($this->type) &&
            $revision < $config->get($this->type . '.DefinitionRev')
        ) return true;
        return false;
    }
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.