HTTP/2 Unencrypted Connection Vulnerability in Go Programming Language
CVE-2026-56853

7.5HIGH

Key Information:

Vendor

Go Standard Library

Status
Net/http
Vendor
CVE Published:
13 August 2026

What is CVE-2026-56853?

The vulnerability in the Go programming language's HTTP/2 server arises when it is configured to process unencrypted HTTP/2 connections. During the initial connection phase, the server fails to apply the ReadHeaderTimeout appropriately while inspecting incoming connection bytes for the HTTP/2 client preface. This can lead to potential service disruptions or higher susceptibility to specific types of attacks, as the usual timeout protections are ineffective in this scenario.

Affected Version(s)

net/http 0 < 1.25.13

net/http 1.26.0-0 < 1.26.6

net/http 1.27.0-0 < 1.27.0-rc.3

References

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

CVSS V3.1

Score:
7.5
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.