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
- www.cve.org/CVERecord ↗
- nvd.nist.gov/vuln/detail/CVE-2026-33943 ↗
- github.com/capricorn86/happy-dom/commit/5437fdf8f13adb9590f9f52616d9f69c3ee8db3c ↗
- github.com/capricorn86/happy-dom/releases/tag/v20.8.8 ↗
- github.com/capricorn86/happy-dom/security/advisories/GHSA-6q6h-j7hj-3r64 ↗
- access.redhat.com/security/cve/CVE-2026-33943 ↗
- bugzilla.redhat.com/show_bug.cgi ↗
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33943.json ↗
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This product uses the NVD API but is not endorsed or certified by the NVD. CVSS scores do not establish exploitation.