In IoTivity through 1.3.1, the CoAP server interface can be used for Distributed Denial of Service attacks using source IP address spoofing and UDP-based traffic amplification. The reflected traffic is 6 times bigger than spoofed requests. This occurs because the construction of a "4.01 Unauthorized" response is mishandled. NOTE: the vendor states "While this is an interesting attack, there is no plan for maintainer to fix, as we are migrating to IoTivity Lite."