Excessive CPU Consumption in Go HTTP/2 by Malicious Peers
CVE-2026-78669

7.5HIGH

Key Information:

Vendor

Go Standard Library

Status
Net/http
Net/http/internal/http2
Golang.org/x/net/http2
Vendor
CVE Published:
8 October 2026

What is CVE-2026-78669?

A vulnerability in the Go HTTP/2 implementation allows a malicious peer to exploit the protocol by creating an excessive number of streams, leading to significant CPU consumption. By sending numerous SETTINGS frames with adjusted SETTINGS_INITIAL_WINDOW_SIZE values, attackers can overwhelm the server or client, resulting in degraded performance or service outages.

Affected Version(s)

golang.org/x/net/http2 0 < 0.60.0

net/http 0 < 1.26.9

net/http/internal/http2 1.27.0-0 < 1.27.2

References

https://go.dev/cl/847186
https://go.dev/cl/847308
https://go.dev/issue/81742

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

Credit

Jakub Ciolek (https://ciolek.dev)
.