Log in Start free

Vulnerability · Published Mar 27, 2026 · Assigned by GitHub_M

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

High 8.8

In plain English

A high-severity code injection in happy-dom from capricorn86. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 51% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)8.8High
Exploit odds (30 days)0.6%top 48.8% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
npmhappy-dom20.8.8GHSA-6q6h-j7hj-3r64

Affected products (as reported)

VendorProductVersions
capricorn86 happy-dom >= 15.10.0, < 20.8.8

Weakness: CWE-94, CWE-917 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

References