How to set user list not accessible

Hi !

I'm testing PunBB to give access for a small group of moderators to all the forums, on the other side guest can access to one forum but not to the restricted forums.
Everything running well except that a guest can access to the user list (including moderator, admin)

I have not seen any option to disable the access to the user list ... is it correct ?
Is there any solution to this problem ?

If the option doesn't exist is there any way to browse the user list for a guest with the "user" choice only, by removing moderator and admin choice ?

help will be appreciated.

regards.

Pat