Description

When parsing a Range header containing a large number of small ranges, FileServer(FS), ServeContent, and ServeFile(FS) can consume an excessive amount of CPU.

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References

Other References

https://go.dev/cl/847309 https://go.dev/issue/81858 https://groups.google.com/g/golang-announce/c/U2fTuyDJznI https://pkg.go.dev/vuln/GO-2026-6609

Frequently Asked Questions

What is CVE-2026-78667? +

When parsing a Range header containing a large number of small ranges, FileServer(FS), ServeContent, and ServeFile(FS) can consume an excessive amount of CPU.

How do I check if I'm vulnerable to CVE-2026-78667? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.