You can try the nav menu roles plugin. It works well as long as it’s compatible with your theme.
In fact, I prefered to do iy myself. It’s not specific to bbpress and I’m very surprised that WP doesn’t have this feature natively.
For the ones who nedd this, here is my simple code :
function yournamespace_exclude_menu_items( $items, $menu, $args ) {
// only hide items in front, not admin
if ( !is_admin() ) {
// Iterate over the items
foreach ( $items as $key => $item ) {
// hide menu items which leads to pages with 'private' status
if ( !is_user_logged_in() && get_post_status($item->object_id) == 'private' ) unset( $items[$key] );
}
return $items;
}
else return $items;
}
add_filter( 'wp_get_nav_menu_items', 'yournamespace_exclude_menu_items', null, 3 );