[Dave]

You must pass 'acnt_settings' => true to the 'extra' array. Based on the code that allows you to edit the email/password as a regular user and also includes current password verification.

You need to extract the userid from the current session returned by vBulletin and not from a cookie because I can just simply use a cookie editor to edit my bbuserid cookie to the userid of an administrator and then hijack the account.