[Asbjørn Ulsberg]

After some more digging, I’ve found that the perpetrator is the db_connect() function inside class.bpdb-multi.php. I don’t understand why that file should be in use on a non-multi WP/bbPress installation, but either way it’s that file that does the offensive db_connect_host() call with erroneous credentials, host, etc.

What’s really weird is that the front page of bbPress works, while opening a topic yields the “Access denied for user ‘admin’@’localhost’ (using password: YES)” error message. Why would class.bpdb-multi.php be in use on a topic page but not on the front page? Makes no sense.