What’s Vulnerable › Vulnerabilities

CVE-2026-118659: @happy-dom/server-renderer: ServerRendererServer Target-Origin Bypass SSRF / Open Proxy

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-28 · updated 2026-10-29
• Weakness: CWE-918

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.

Affected products

• capricorn86 happy-dom: before 21.0.2

References

• https://github.com/capricorn86/happy-dom/commit/1f3ffdf634231361de1a2acb629b4fe8ee1bd85d
• https://github.com/capricorn86/happy-dom/pull/2520
• https://github.com/capricorn86/happy-dom/releases/tag/v21.0.2
• https://github.com/capricorn86/happy-dom/security/advisories/GHSA-pmf4-3xr3-xjhg
• https://github.com/capricorn86/happy-dom/security/advisories/GHSA-pmf4-3xr3-xjhg

Get alerted when CVE-2026-118659 or the next vulnerability affects your stack