---
title: "CVE-2026-78669: HTTP/2 - Denial of Service"
description: "HTTP/2 protocol contains a denial of service vulnerability caused by excessive CPU consumption from many small SETTINGS frames with SETTINGS_INITIAL_WINDOW_SIZE values, letting malicious peers cause resource exhaustion, exploit requires a malicious HTTP/2 peer."
url: https://panop.io/threat-heartbeat/CVE-2026-78669/
---

# CVE-2026-78669 HTTP/2 - Denial of Service

HTTP/2 protocol contains a denial of service vulnerability caused by excessive CPU consumption from many small SETTINGS frames with SETTINGS\_INITIAL\_WINDOW\_SIZE values, letting malicious peers cause resource exhaustion, exploit requires a malicious HTTP/2 peer.

CVSS base score 7.5 /10

High

CISA KEV

Not listed

Public exploit

None known

EPSS

0.57% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-78669)

## Details

Type

Denial of Service

Impact

Denial Of Service

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Published

8 October 2026

Updated

15 October 2026

Weakness

[CWE-405](https://cwe.mitre.org/data/definitions/405.html)

## Vendor fix

Update to the latest version with HTTP/2 protocol fixes.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-78669](https://nvd.nist.gov/vuln/detail/CVE-2026-78669)
- [https://go.dev/cl/847186](https://go.dev/cl/847186)
- [https://go.dev/cl/847308](https://go.dev/cl/847308)
- [https://go.dev/issue/81742](https://go.dev/issue/81742)
- [https://groups.google.com/g/golang-announce/c/U2fTuyDJznI](https://groups.google.com/g/golang-announce/c/U2fTuyDJznI)
- [https://groups.google.com/g/golang-announce/c/ZPwCyRUuGBs](https://groups.google.com/g/golang-announce/c/ZPwCyRUuGBs)
- [https://pkg.go.dev/vuln/GO-2026-6611](https://pkg.go.dev/vuln/GO-2026-6611)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

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