CVE-2026-56853

HIGH 7.5

Apply ReadHeaderTimeout when doing unencrypted HTTP/2 check in net/http

CVSS Score

7.5

EPSS Score

0.2%

EPSS Percentile

13th

When a server is configured to support unencrypted HTTP/2, it reads a few bytes from each new connection to see if they contain the HTTP/2 client preface. ReadHeaderTimeout is unexpectedly not being applied when doing this.

Vendor	go standard library
Product	net/http
Published	Aug 13, 2026
Last Updated	Aug 14, 2026

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Affected Versions

Go standard library / net/http

0 < 1.25.13 1.26.0-0 < 1.26.6 1.27.0-0 < 1.27.0-rc.3

References

NVD ↗ CVE.org ↗ EPSS Data ↗

go.dev: https://go.dev/issue/80205 go.dev: https://go.dev/cl/795540 groups.google.com: https://groups.google.com/g/golang-announce/c/94pEornpRlI pkg.go.dev: https://pkg.go.dev/vuln/GO-2026-6089