Waveshare RS232/485 TO WIFI ETH (B) Serial to Ethernet/Wi-Fi Gateway Firmware V3.1.1.0: HW 4.3.2.1: Webpage V7.04T.07.002880.0301 allows attackers to set the Administrator password and username as blank values, allowing attackers to bypass authentication.
When setting a new password for a user, the product does not require knowledge of the original password, or using another form of authentication.