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.
History

Fri, 06 Nov 2026 00:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

threat_severity

Moderate


Thu, 29 Oct 2026 20:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 28 Oct 2026 22:15:00 +0000

Type Values Removed Values Added
First Time appeared Capricorn86
Capricorn86 happy-dom
Vendors & Products Capricorn86
Capricorn86 happy-dom

Wed, 28 Oct 2026 20:30:00 +0000

Type Values Removed Values Added
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.
Title @happy-dom/server-renderer: ServerRendererServer Target-Origin Bypass SSRF / Open Proxy
Weaknesses CWE-918
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published: 2026-10-28T20:20:29.561Z

Updated: 2026-10-29T18:27:45.701Z

Reserved: 2026-10-28T17:25:37.561Z

Link: CVE-2026-118659

cve-icon Vulnrichment

Updated: 2026-10-29T18:27:35.393Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-10-28T21:16:55.967

Modified: 2026-10-29T19:17:18.813

Link: CVE-2026-118659

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-10-28T20:20:29Z

Links: CVE-2026-118659 - Bugzilla