CVE-2026-33943

CRITICAL EPSS 50.1%
Published Mar 27, 20263mo ago · Modified Jun 17, 20262w ago
9.8 CVSS 3.1
Critical
Find Similar
Published Mar 27, 2026 3mo ago
Last Modified Jun 17, 2026 2w ago

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.

CVSS Details

Base Score
9.8
Exploitability
3.9
Impact
5.9
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality High
Integrity High
Availability High

Threat Intelligence

EPSS Exploit Probability
50.1% percentile
Exploit & Patch Status
Public Exploit Known
Patch Available

Weaknesses 1

CWE-94 Improper Control of Generation of Code (Code Injection) Injection

Affected Products 1

VendorProductVersionRange
capricorn86happy_dom*≥15.10.0  –  <20.8.8

References 3

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

Remediation

  • github.com https://github.com/capricorn86/happy-dom/commit/5437fdf8f13adb9590f9f52616d9f69c3ee8db3c
    Patch