CVE-2026-33943 HIGH

CVE-2026-33943: Happy DOM ECMAScriptModuleCompiler: unsanitized export names are interpolated as executable code

Vendor Capricorn86
Product happy-dom
Weakness CWE-94 · Code injection
Published March 27, 2026
Last update June 30, 2026
View on NVD All CVEs

CVSS base score

8.8/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction Required
Confidentiality High
Integrity High

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

What the vulnerability does

01Description

Happy DOM is a JavaScript implementation of a web browser without its graphical user interface. In versions 15.10.0 through 20.8.7, a code injection vulnerability in `ECMAScriptModuleCompiler` allows an attacker to achieve Remote Code Execution (RCE) by injecting arbitrary JavaScript expressions inside `export { }` declarations in ES module scripts processed by happy-dom. The compiler directly interpolates unsanitized content into generated code as an executable expression, and the quote filter does not strip backticks, allowing template literal-based payloads to bypass sanitization. Version 20.8.8 fixes the issue.

Key dates

02Disclosure timeline

March 27, 2026 CVE published
June 30, 2026 Record updated