CVE-2026-118659

Received Received - Intake

Path Traversal in Happy DOM Server-Renderer

Publication date: 2026-10-28

Last updated on: 2026-10-28

Assigner: GitHub, Inc.

Description

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.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-10-28

Last Modified

2026-10-28

Generated

2026-10-29

AI Q&A

2026-10-29

EPSS Evaluated

N/A

NVD

CVE-2026-118659

EUVD

EUVD-2026-112466

Affected Vendors & Products

Vendor	Product	Version / Range
capricorn86	happy-dom	< 21.0.2

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-918	The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.

Attack-Flow Graph

Executive Summary

Happy DOM is a JavaScript browser implementation. Prior to version 21.0.2, the server-renderer package accepted unauthenticated HTTP/2 requests and processed attacker-controlled paths without verifying if the resolved origin remained trusted. This allowed attackers to redirect requests to arbitrary endpoints, including internal services, and receive responses.

Impact Analysis

An attacker could exploit this to send requests to internal or external services on your behalf, potentially accessing sensitive data or internal resources. This could lead to data leaks, unauthorized access, or service disruption if misused.

Compliance Impact

This vulnerability could violate GDPR by enabling unauthorized data access or exfiltration. For HIPAA, it may risk exposing protected health information if internal services are targeted. Compliance depends on the specific data processed and affected systems.

Mitigation Strategies

Update Happy DOM to version 21.0.2 or later to address the vulnerability in the server-renderer package.

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