The weak password on the web user interface can be exploited via HTTP or HTTPS. Once such access has been obtained, the other passwords can be changed. The weak password on Linux accounts can be accessed via SSH or Telnet, the former of which is by default enabled on trusted interfaces. While the SSH service does not support root login, a user logging in using either of the other Linux accounts may elevate to root access using the su command if they have access to the associated password.
CWE-521, CWE-521