CVE-2026-33943

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.

References

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