bbPress.org

@ mykes

I double checked, the latest stable version of WordPress MU uses the old password hashing and cookie types.

You can dumb down bbPress to work with that version of WordPress MU by using both of these bbPress plugins.

https://bbpress.org/plugins/topic/mouldy-old-cookies-for-bbpress/

https://bbpress.org/plugins/topic/md5-insecurity-for-bbpress/