A password can be set for the meeting wall and will restrict a person from joining your meeting through the browser or by clicking on a meeting invite link. If the person downloads the desktop app, it does not ask for a password. This seem like an app vulnerability.
Hello,
Password on the wall is not to prevent users from joining to your meeting. It is to protect information on the wall (such as meeting resources and calendar) from unauthorized access.
To join the meeting participants do not even need the desktop or mobile app they simply can dial in using regular phone and enter the access code.
If security is a concern please change your online meeting Id and the access code after every meeting.
Thank you,
Eugene