---
id: CVE-2026-78660
title: >-
  Historically, we have been rather lax about malformed framing-related headers
  in our HTTP/2 implementation, as they cannot interfere with HTTP/2 framing
summary: >-
  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 …
severity: none
published: '2026-10-08'
updated: '2026-10-08'
sourceUpdated: '2026-10-08T23:17:03.510'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-78660'
references:
  - url: 'https://go.dev/cl/835145'
    label: security@golang.org
  - url: 'https://go.dev/cl/836385'
    label: security@golang.org
  - url: 'https://go.dev/issue/81115'
    label: security@golang.org
  - url: 'https://groups.google.com/g/golang-announce/c/U2fTuyDJznI'
    label: security@golang.org
  - url: 'https://pkg.go.dev/vuln/GO-2026-6610'
    label: security@golang.org
tags:
  - nvd
ingestedAt: '2026-10-09T00:19:50.975Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.