CVE-2026-33943

HIGH 8.8

Happy DOM ECMAScriptModuleCompiler: unsanitized export names are interpolated as executable code

CVSS Score

8.8

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-94
Vendor	capricorn86
Product	happy-dom
Published	Mar 27, 2026
Last Updated	Mar 27, 2026

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CVSS v3 Breakdown

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

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Affected Versions

capricorn86 / happy-dom

>= 15.10.0, < 20.8.8

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/capricorn86/happy-dom/security/advisories/GHSA-6q6h-j7hj-3r64 github.com: https://github.com/capricorn86/happy-dom/commit/5437fdf8f13adb9590f9f52616d9f69c3ee8db3c github.com: https://github.com/capricorn86/happy-dom/releases/tag/v20.8.8