The password change function at /cgi/admin.cgi does not require the current/old password, which makes the application vulnerable to account takeover. An attacker can use this to forcefully set a new password within the -rsetpass+-aaction+- parameter for a user without knowing the old password, e.g. by exploiting a CSRF issue.
When setting a new password for a user, the product does not require knowledge of the original password, or using another form of authentication.