---
id: "CVE-2026-118659"
kind: "vulnerability"
aliases: ["CVE-2026-118659"]
title: "Happy DOM: server renderer proxies unauthenticated requests to internal services"
severity: "high"
cvss: 7.5
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["happy-dom", "node", "package", "self-hosted", "server-side-rendering"]
not_affected_if: ["client-only-use", "no-server-renderer"]
published_at: "2026-10-28T21:16:55+00:00"
first_seen_at: "2026-10-28T21:35:45+00:00"
updated_at: "2026-10-28T21:36:36+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-118659", "first_seen_at": "2026-10-28T21:35:45+00:00"}]
---

# Happy DOM: server renderer proxies unauthenticated requests to internal services

Happy DOM's server-renderer package accepts unauthenticated HTTP/2 requests and resolves protocol-relative paths against its target origin without checking the destination. An attacker can make the server fetch arbitrary HTTP or HTTPS endpoints, including local and internal services, and receive the response headers and body back.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed version of `@happy-dom/server-renderer` with `npm ls @happy-dom/server-renderer`
- Confirm whether the ServerRendererServer is running and reachable from untrusted networks (unknown from sources)

## Fix

- Upgrade `@happy-dom/server-renderer` to `21.0.2` or later
- Restrict network access to the renderer server until upgraded (unknown from sources for other mitigations)

## Timeline

- 2026-10-28T21:35:45+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-118659

## From the sources

Happy DOM is a JavaScript implementation of a web browser without its graphical user interface. Prior to 21.0.2, the Happy DOM server-renderer package's ServerRendererServer accepts unauthenticated HTTP/2 requests and resolves attacker-controlled :path values against server.targetOrigin in #onIncomingRequest in packages/@happy-dom/server-renderer/src/ServerRendererServer.ts without confirming that the resolved origin remains trusted before calling fetch. A protocol-relative path can change the destination to an arbitrary HTTP or HTTPS endpoint reachable by the server, including local and internal services, and the proxy relays the fetched response headers and body to the requester. This issue is fixed in version 21.0.2.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_