OK. Here's the deal. Yes, there was a rather spectacular vulnerability associated with Cloudflare. However, obtaining the information from the vulnerability is random as it can possibly get. The vulnerability is impossible to use as a targeted attack.
Here's a rather sensible piece from CNN about this whole thing. Ignore the grand standing by some sites who are claiming the sky is falling (it's not).
Why you shouldn't freak out (yet) about the 'Cloudbleed' security leak
For now, the vulnerability is a minor thing as far as the release of sensitive information is concerned. However, we may find tomorrow that people have been slurping data since September and have amassed a rather nasty collection of PMs, chats and passwords. It's unlikely, but it is possible. So for now, it's not something to get worked up about, but taking the standard precautions (password changes) on any site you have an account on and uses Cloudflare would be prudent.