We're compiling a list of affected domains using several scrapers here:

https://github.com/pirate/sites-using-cloudflare

I ranked your list of Cloudflare-using domains by their Alexa rank.

Sharing here in case anyone else finds it useful

(warning - it's 1.1MiB gzipped / 2.4MiB uncompressed)

https://polarisedlight.com/tmp/cf_ranked.txt

any domains outside the top 1 million are ommitted

Hacked this together to determine which ones out of the list are potentially using cloudflare reverse proxies. You could also send an HTTP request to them and look for the cloudflare-nginx Server header.

https://gist.github.com/dustyfresh/4d8d364ca4c6da465cfc7d817...

You can check IP whois records, but it'll be very hard to be 100% sure about any of them. For example, one of the examples from the bug report is Uber, which doesn't use Cloudflare for its home page but apparently does for one of its internal API endpoints.

There is a chrome extension named "claire"[1] which tells you if they use CloudFlare or not, but not sure about other browser (FF or else).

[1]: https://chrome.google.com/webstore/detail/claire/fgbpcgddpmj...

For Firefox, I just made this: https://github.com/traktofon/cf-detect

At this point, I would just start rolling everything. (And I have.)