Security Flaw In Yahoo Mail Exposes Plaintext Authentication Info
I haven't looked carefully at the rest of the platforms that Yahoo provides, but I believe that at least Yahoo Messenger (when connecting with Pidgin anyway) also sends the same auth credentials in plain text. Not that the overall problem is insignificant (*any* time auth credentials are sent, in any context, they should be encrypted), but worrying only about IMAP is naive in this case. (What about POP? What about all the Y! web platforms?)
Yahoo! POP is SSL encrypted (and only available to pro acount users in any case). Part of the worry for me is Yahoo! doesn't disclose that the connection is unencrypted in the default program, and there is no way to get it to use encryption (the server doesn't even support encryption).
As far as other Yahoo! properties I have no idea.