The bug prevents users from changing their email address from the control panel. It always responds with "The current password you entered is incorrect." Even though I am certain the password is correct.
From some quick googling, I think this is a bug in phpBB when using an external user database. The external password and the phpBB password somehow aren't linked properly, causing issues in the UCP.
Can someone else try to change their password from the User Control Panel and confirm that this isn't just me?
User Control Panel -> Profile -> Edit Account Settings