CVE-2026-78660

UNKNOWN 0.0

HTTP/2 transport accepts malformed framing-related headers in net/http

CVSS Score

0.0

EPSS Score

0.0%

EPSS Percentile

0th

Historically, we have been rather lax about malformed framing-related headers in our HTTP/2 implementation, as they cannot interfere with HTTP/2 framing. However, this makes it possible for our HTTP/2 implementation to forward responses containing such headers to an HTTP/1 client when acting as a reverse proxy. If the HTTP/1 client also does not behave strictly enough, this can result in response smuggling.

Vendor	go standard library
Product	net/http
Published	Oct 8, 2026

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Affected Versions

Go standard library / net/http

0 < 1.26.9

Go standard library / net/http/internal/http2

1.27.0-0 < 1.27.2

golang.org/x/net / golang.org/x/net/http2

0 < 0.60.0

References

NVD ↗ CVE.org ↗ EPSS Data ↗

go.dev: https://go.dev/cl/835145 go.dev: https://go.dev/cl/836385 go.dev: https://go.dev/issue/81115 groups.google.com: https://groups.google.com/g/golang-announce/c/U2fTuyDJznI pkg.go.dev: https://pkg.go.dev/vuln/GO-2026-6610

Credits

TJ Barton