Server-Side Request Forgery (SSRF) in Happy DOM - CVE-2026-118660
Published: November 12, 2026
Vulnerability identifier: #VU165953
CSH Severity: High
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:L/SI:N/SA:N]
CVE-ID: CVE-2026-118660
CWE-ID: CWE-918
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to disclose cloud credentials and sensitive internal data through server-side request forgery.
The vulnerability exists due to unrestricted server-side resource loading in Happy DOM's HTML parser when processing untrusted HTML with default settings. A remote attacker can supply HTML containing <iframe src="http://169.254.169.254/latest/meta-data/iam/security-credentials/"></iframe> or <link rel="stylesheet" href="http://127.0.0.1:9995/stylesheet-ssrf"> to trigger requests to internal services or cloud metadata endpoints and disclose sensitive responses.
Affected software
Happy DOM
How to mitigate CVE-2026-118660
Install security update from vendor's website.
Happy DOM - update to 21.0.0