CVE-2026-33943Happy DOM ECMAScriptModuleCompiler: unsanitized export names are interpolated as executable code

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.

Data: CVE.org, NVD, CISA KEV, FIRST EPSS, Ubuntu. Published as the sources state it, in English.

Affected products and versions

References and patches

• https://github.com/capricorn86/happy-dom/security/advisories/GHSA-6q6h-j7hj-3r64 ExploitVendor Advisory
• https://github.com/capricorn86/happy-dom/commit/5437fdf8f13adb9590f9f52616d9f69c3ee8db3c Patch
• https://github.com/capricorn86/happy-dom/releases/tag/v20.8.8 ProductRelease Notes
• https://access.redhat.com/security/cve/CVE-2026-33943
• https://bugzilla.redhat.com/show_bug.cgi?id=2452522
• https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33943.json