[cheald]

It's plenty secure in the sense that you can't forge a session. It's not secure in the sense that the data is inaccessible if you know how to base64 decode a cookie.

If you're using cookie sessions, you should know better than to store sensitive information in the session.

[chris_wot]

In other words, because they are holding sensitive information in their cookies encoded only via base64 it's not secure. In other words, what I said.