CVE-2021-34204
D-Link DIR-2640-US 1.01B04 is affected by Insufficiently Protected Credentials. D-Link AC2600(DIR-2640) stores the device system account password in plain text. It does not use linux user management. In addition, the passwords of all devices are the same, and they cannot be modified by normal users. An attacker can easily log in to the target router through the serial port and obtain root privileges.
Source: CVE-2021-34204