# CVE-2026-78669 — Go standard library net/http

> As of 2026-10-09, CVE-2026-78669 is a HIGH-severity vulnerability in Go standard library net/http, CVSS v3.1 7.5, EPSS 0.2% (12.3th percentile). No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-78669 as of 2026-10-09; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

**Last updated:** 2026-10-09

## What is CVE-2026-78669?

A malicious HTTP/2 peer can cause excessive CPU consumption in the client or server by opening a large number of streams and then sending many small SETTINGS frames containing SETTINGS_INITIAL_WINDOW_SIZE values.

The record classifies CVE-2026-78669 under weakness class [CWE-405](https://intel.threadlinqs.com/cwe/CWE-405). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on availability. 3 affected-product entries are recorded, across 2 vendors, listed below. The identifier was first published 2 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 7.5 — HIGH (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **EPSS (FIRST):** 0.2% probability of exploitation in the next 30 days, higher than 12.3% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 4.2/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-10-08, last modified 2026-10-09

## Is CVE-2026-78669 being exploited?

It currently carries a trending score of 33 in the Threadlinqs vulnerability feed.

## Affected products and versions

- [Go standard library](https://intel.threadlinqs.com/vendors/go-standard-library): net/http, net/http/internal/http2
- **golang.org/x/net**: golang.org/x/net/http2

## How to fix CVE-2026-78669

No vendor patch reference has been recorded for CVE-2026-78669 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-78669

No threat campaign in the Threadlinqs corpus currently references CVE-2026-78669, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

## Sources

Enriched from CVE.org, NVD, FIRST EPSS. Last verified by Threadlinqs on 2026-10-10. This product uses the NVD API but is not endorsed or certified by the NVD.

**Other references**

- [go.dev](https://go.dev/cl/847186)
- [go.dev (847308)](https://go.dev/cl/847308)
- [go.dev (81742)](https://go.dev/issue/81742)
- [groups.google.com](https://groups.google.com/g/golang-announce/c/U2fTuyDJznI)
- [groups.google.com (ZPwCyRUuGBs)](https://groups.google.com/g/golang-announce/c/ZPwCyRUuGBs)

_Showing 5 of 6 recorded references._

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-78669
Full detection coverage and IOCs for threats exploiting CVE-2026-78669 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp