Hard-coded Credentials Vulnerability in ZKTeco WL20

This vulnerability exists in ZKTeco WL20 due to hard-coded MQTT credentials and endpoints stored in plaintext within the device firmware. An attacker with physical access could exploit this vulnerability by extracting the firmware and analyzing the binary data to retrieve the hard-coded MQTT credentials and endpoints from the targeted device. Successful exploitation of this vulnerability could allow the attacker to gain unauthorized access to the MQTT broker and manipulate the communications of the targeted device.