Cloudflare fixes CDN code execution bug affecting 12.7% of all sites

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Cloudflare has fixed a critical vulnerability in its free and open-source CDNJS potentially impacting 12.7% of all websites on the internet.

CDNJS serves millions of websites with over 4,000 JavaScript and CSS libraries stored publicly on GitHub, making it the second-largest JavaScript CDN.

The vulnerability exploits comprised publishing packages to Cloudflare's CDNJS using GitHub and npm, to trigger a Path Traversal vulnerability, and eventually remote code execution.

If exploited, the vulnerability would lead to a complete compromise of CDNJS infrastructure.
"While this vulnerability could be exploited without any special skills, it could impact many websites."

"Given that there are many vulnerabilities in the supply chain, which are easy to exploit but have a large impact, I feel that it's very scary," says RyotaK in his blog post.

As previously reported by BleepingComputer, a Magecart supply-chain attack impacting thousands of online stores stemmed from the compromise of Volusion's CDN infrastructure.

The researcher praised Cloudflare's fast-paced incident response teams, who, within minutes of receiving the researcher's report, rotated the leaked secrets and worked with him to study the PoC exploits.

BleepingComputer has reached out to Cloudflare with some questions, including if this vulnerability has been widely exploited. We are awaiting their response.