CVE-2026-33943
Happy 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.
INFO
Published Date :
March 27, 2026, 10:16 p.m.
Last Modified :
April 13, 2026, 5:24 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 3.1 | HIGH | MITRE-CVE | ||||
| CVSS 3.1 | CRITICAL | [email protected] |
Solution
- Update happy-dom to version 20.8.8 or later.
- Review and sanitize all user-supplied input for module scripts.
- Validate that exported expressions do not contain malicious code.
Public PoC/Exploit Available at Github
CVE-2026-33943 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-33943.
| URL | Resource |
|---|---|
| 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://github.com/capricorn86/happy-dom/security/advisories/GHSA-6q6h-j7hj-3r64 | Exploit Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-33943 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-33943
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
None
Java Shell Batchfile Dockerfile HTML JavaScript TypeScript CSS EJS SCSS
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-33943 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-33943 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Apr. 13, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Added CPE Configuration OR *cpe:2.3:a:capricorn86:happy_dom:*:*:*:*:*:node.js:*:* versions from (including) 15.10.0 up to (excluding) 20.8.8 Added Reference Type GitHub, Inc.: https://github.com/capricorn86/happy-dom/commit/5437fdf8f13adb9590f9f52616d9f69c3ee8db3c Types: Patch Added Reference Type GitHub, Inc.: https://github.com/capricorn86/happy-dom/releases/tag/v20.8.8 Types: Product, Release Notes Added Reference Type CISA-ADP: https://github.com/capricorn86/happy-dom/security/advisories/GHSA-6q6h-j7hj-3r64 Types: Exploit, Vendor Advisory Added Reference Type GitHub, Inc.: https://github.com/capricorn86/happy-dom/security/advisories/GHSA-6q6h-j7hj-3r64 Types: Exploit, Vendor Advisory -
New CVE Received by [email protected]
Mar. 27, 2026
Action Type Old Value New Value Added 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. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Added CWE CWE-94 Added Reference https://github.com/capricorn86/happy-dom/commit/5437fdf8f13adb9590f9f52616d9f69c3ee8db3c Added Reference https://github.com/capricorn86/happy-dom/releases/tag/v20.8.8 Added Reference https://github.com/capricorn86/happy-dom/security/advisories/GHSA-6q6h-j7hj-3r64 -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Mar. 27, 2026
Action Type Old Value New Value Added Reference https://github.com/capricorn86/happy-dom/security/advisories/GHSA-6q6h-j7hj-3r64