TRENDnet TEW-827DRU devices through 2.06B04 contain a stack-based buffer overflow in the ssi binary. The overflow allows an authenticated user to execute arbitrary code by POSTing to apply.cgi via the action st_dev_connect, st_dev_disconnect, or st_dev_rconnect with a sufficiently long wan_type key.
github.com/kuc001/IoTFirmware/blob/master/Trendnet/TEW-827/st_dev_connect_overflow.pdf
github.com/kuc001/IoTFirmware/blob/master/Trendnet/TEW-827/st_dev_disconnect_overflow.pdf
github.com/kuc001/IoTFirmware/blob/master/Trendnet/TEW-827/st_dev_rconnect_overflow.pdf
github.com/kuc001/IoTFirmware/blob/master/Trendnet/TEW-827/TRENDnet-st_dev.pdf