Windu CMS is vulnerable to User Enumeration. This issue occurs during logon, where a difference in messages could allow an attacker to determine if the login is valid or not, enabling a brute force attack with valid logins.
The vendor was notified early about this vulnerability, but didn't respond with the details of vulnerability or vulnerable version range. Only version 4.1 was tested and confirmed as vulnerable, other versions were not tested and might also be vulnerable.