The Grandstream HT-488 0.1 allows remote attackers to cause a denial of service (device crash) via a flood of fragmented packets to port 5060.
https://exchange.xforce.ibmcloud.com/vulnerabilities/37414
http://www.sipera.com/index.php?action=resources%2Cthreat_advisory&tid=362
http://www.securityfocus.com/bid/26349