I have one of these connected within my home network. Considering how it is connected, I see no potential problem. My Bridge connects to the home 5G wifi and its output is to ethernet port on back which is connected to the wired input ethernet port on a WDTV. It is NOT directly connected to the internet at all. If this device was vulnerable, everything in the house connected to router would be! The router is an Asus, and has a firewall, etc, so nothing is vulnerable.
As for firmware, there was only one release of FW, and I have a copy on this PC. The file name is My_Net_AC_Wi-Fi_Bridge_1.02.01.bin
Google to find a copy somewhere.