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.
Fix
Patch, vendor advisory and mitigation references on NVD 3
- https://github.com/capricorn86/happy-dom/commit/5437fdf8f13adb9590f9f52616d9f69c3ee8db3c Patch
- https://github.com/capricorn86/happy-dom/security/advisories/GHSA-6q6h-j7hj-3r64 Exploit, Vendor Advisory
- https://github.com/capricorn86/happy-dom/security/advisories/GHSA-6q6h-j7hj-3r64 Exploit, Vendor Advisory
Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.
Change history 1
- First seenCVSS 9.8 · capricorn86NVD modified 2026-10-26 00:10
Affected (CPE criteria) 1
cpe:2.3:a:capricorn86:happy_dom:*:*:*:*:*:node.js:*:*
References 7
- https://github.com/capricorn86/happy-dom/commit/5437fdf8f13adb9590f9f52616d9f69c3ee8db3c Patch
- https://github.com/capricorn86/happy-dom/releases/tag/v20.8.8 Product, Release Notes
- https://github.com/capricorn86/happy-dom/security/advisories/GHSA-6q6h-j7hj-3r64 Exploit, Vendor Advisory
- https://access.redhat.com/security/cve/CVE-2026-33943
- https://bugzilla.redhat.com/show_bug.cgi?id=2452522
- https://github.com/capricorn86/happy-dom/security/advisories/GHSA-6q6h-j7hj-3r64 Exploit, Vendor Advisory
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33943.json