Cloudflare 'CPU Spike' Glitches 16M Sites

John Lister's picture

One of the most important services on the Internet went down for around an hour this week, causing widespread problems on other sites. The glitch is a reminder of how fragile some aspects of the Internet are.

Cloudflare is a website that offers several free and paid services designed to make websites more efficient. Two of its main services are traffic filtering and web caching.

The former involves web traffic between a user and a website going through Cloudflare. During this process, the client machine is checked for signs of malicious activity. This can involve attempted hacking, but also denial of service attacks designed to overload a website and bring it down. The company offers free protection to around 600 non-profit groups who face politically-motivated attempts to knock their sites offline.

The web caching involves Cloudflare creating multiple copies of a website, then re-routes visitors to a copy that's physically stored nearer to their location. This seamlessly eases the load on the website itself without the website operator making drastic changes. It then translates to quicker load times for users. (Source:

"Downdetector" Down

More than 16 million websites use Cloudflare. In an average day, more than a billion IP addresses try to connect to those 16 million sites, so the recent glitch had a significant effect.

Perhaps the most ironic glitch was that the website "Downdetector" became unavailable. It's a site users can visit to check whether a popular site is unavailable for everyone or if there's a problem at their end.

Another awkward outcome was at CoinDesk, a website for news about digital currencies. While the site itself was available, some of the data it received from other sources to provide its news appears to have been corrupted.

That led to some serious problems with the automated content on the site, most notably listing the current value of one Bitcoin as $26. That will have caused a few heart stopping moments for "investors" given the real price is more than $10,000.

No Evidence Of Attack

Cloudflare's chief executive says there's no evidence that the service was hit by a deliberate attack. He says all that's known for certain right now is that Cloudflare's systems had a sudden spike in CPU usage worldwide that caused failover servers to initiate. (Source:

In this case, duplicate (back-up) systems kicked in, which then set off a chain reaction.

What's Your Opinion?

Were you familiar with Cloudflare's services? Are you concerned so many sites are reliant on Cloudflare? Or is it reassuring that such glitches are rare enough to be newsworthy?

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