Vulnerability Description
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.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Capricorn86 | Happy Dom | >= 15.10.0, < 20.8.8 |
Related Weaknesses (CWE)
References
- https://github.com/capricorn86/happy-dom/commit/5437fdf8f13adb9590f9f52616d9f69cPatch
- https://github.com/capricorn86/happy-dom/releases/tag/v20.8.8ProductRelease Notes
- https://github.com/capricorn86/happy-dom/security/advisories/GHSA-6q6h-j7hj-3r64ExploitVendor Advisory
- https://github.com/capricorn86/happy-dom/security/advisories/GHSA-6q6h-j7hj-3r64ExploitVendor Advisory
FAQ
What is CVE-2026-33943?
CVE-2026-33943 is a vulnerability with a CVSS score of 8.8 (HIGH). 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 ...
How severe is CVE-2026-33943?
CVE-2026-33943 has been rated HIGH with a CVSS base score of 8.8/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-33943?
Check the references section above for vendor advisories and patch information. Affected products include: Capricorn86 Happy Dom.