Fixing this now. The password box doesn't seem to have any action, but it still should not be there.
Also, as far as I'm aware the forum software was kept up to date for vulnerabilities and security holes. Although it's a few years old, doing a full upgrade to a newer version would cause quite a bit of downtime and headaches. That is why we're still on this older version. FYI, most other large sites are on even older outdated versions than we are, because of the pain of upgrading. Issues like this happen from time to time, unfortunately.