CVE-2026-118660

High

Description

Happy DOM is a JavaScript implementation of a web browser without its graphical user interface. Prior to 21.0.0, Happy DOM loads iframe src URLs and link rel="stylesheet" href URLs by default while parsing untrusted HTML on the server because disableIframePageLoading and disableCSSFileLoading default to false. An attacker who controls parsed HTML can therefore cause server-side requests to arbitrary internal or cloud endpoints without an application opt-in and may expose confidential responses or credentials returned by those endpoints. This issue is fixed in version 21.0.0.

SeverityHigh

CVSS8.6

Exploit probability—

ProductHappy-dom

PublishedOct 28, 2026

First seenNov 4, 2026

Weakness typeCWE-918Server-side request forgery (SSRF)

How to fix

Update

happy-dom21.0.0 or later

Affected products

Product	Affected versions	Fixed in
happy-domnpm	v ≤ 20.14.6	21.0.0

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