Recently, researchers at Google Zero Project discovered a serious vulnerability in Cloudflare servers. The vulnerability existed because the Cloudflare developers had not implemented some feature properly and it was causing buffer overrun in some cases. This vulnerability is now being called CloudBleed or CloudLeak just like they started calling an OpenSSL vulnerability HeartBleed some time ago. Even though Cloudflare has fixed the bug and worked very hard with all the major search engines to remove all the cached entries that were revealing sensitive information, you are advised to change the login passwords or other credentials of all the sites that use Cloudflare CDN services.
But how would you know if a website uses Cloudflare services or not? This is where CloudBleed browser extension for Firefox and Chrome comes in. This extension can scan your browsing history and enlist all the URLs belonging to domains that make use of the Cloudflare CDN services.
After installing the CloudBleed, you can click on the red heart icon in the toolbar to access the CloudBleed interface. On the CloudBleed page, you can enter the number of days for which you want to search the browser history. As you click on the Search button, it shows you all the URLs belonging to domain names that have been using Cloudflare CDN services.
Just because a domain name uses Cloudflare, does not necessarily mean that your login information associated with website was leaked or cached by the search engines. Instead of getting scared by the long list of URLs that are displayed by CloudBleed, you should take the precautionary measure to change the login credentials or passwords belonging to these sites. You can use our PassGen portable program to generate very strong passwords for this purpose.
Conclusion: CloudBleed was a bug in Cloudflare servers and was very professionally handled by the Cloudflare people. But you can still find all the URLs that you have already visited in your browsers using the CLoudBleed extension so that you can change the passwords of your accounts on these sites.
You can get the CloudBleed Firefox extension from https://addons.mozilla.org/en-US/firefox/addon/cloudbleed/ and the CloudBleed Chrome extension from https://chrome.google.com/webstore/detail/cloudbleed/gmbmbodfgolnnfhfanhjeodfambaoklj.