You may have already heard about the Cloudflare memory leak reported in their official blog post. It's being reported today by many of the 4,287,625 possibly affected domains receiving notice of the issue.

This morning, at 7am EST, we received an email from Cloudflare notifying us of the now patched bug and summarizing the current status of their findings.

From the blog posts and email below, we understand the Cloudflare memory leak bug affected all of their 4+ millions sites but they have "yet to find any instance of the bug being exploited". They specifically reached out to the 150 sites they found sensitive information in third party caches, we are not one of the domains and they will reach out to us directly if that changes. However, because of how wide spread this bug is, it's a good idea to change your password, particularly if it's weak.

We'll keep the community informed on any further updates from Cloudflare.

The email:

Thursday afternoon, we published a blog post describing a memory leak caused by a serious bug that impacted Cloudflare's systems. If you haven't yet, I encourage you to read that post on the bug:

blog.cloudflare.com/incident-report-on-memory-leak-caused-by-cloudflare-parser-bug/

While we resolved the bug within hours of it being reported to us, there was an ongoing risk that some of our customers' sensitive information would still be available through third party caches, such as the Google search cache.

Over the last week, we've worked with these caches to discover what customers may have had sensitive information exposed and ensure that the caches are purged. We waited to disclose the bug publicly until after these caches could be cleared in order to mitigate the ability of malicious individuals to exploit any exposed data.

In our review of these third party caches, we discovered exposed data on approximately 150 of Cloudflare's customers across our Free, Pro, Business, and Enterprise plans. We have reached out to these customers directly to provide them with a copy of the data that was exposed, help them understand its impact, and help them mitigate that impact.

Your domain is not one of the domains where we have discovered exposed data in any third party caches. The bug has been patched so it is no longer leaking data. However, we continue to work with these caches to review their records and help them purge any exposed data we find. If we discover any data leaked about your domains during this search, we will reach out to you directly and provide you full details of what we have found.

To date, we have yet to find any instance of the bug being exploited, but we recommend if you are concerned that you invalidate and reissue any persistent secrets, such as long lived session identifiers, tokens or keys. Due to the nature of the bug, customer SSL keys were not exposed and do not need to be rotated.

Again, if we discover new information that impacts you, we will reach out to you directly. In the meantime, if you have any questions or concerns, please don’t hesitate to reach out.

Matthew Prince
Cloudflare, Inc.
Co-founder and CEO