N/A

CVSS Score

-

CVSS Score

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CVE-2025-61927

CVE-2025-61927: Happy DOM: VM Context Escape can lead to Remote Code Execution

Escape of VM Context gives access to process level functionality

Summary

Happy DOM v19 and lower contains a security vulnerability that puts the owner system at the risk of RCE (Remote Code Execution) attacks.

A Node.js VM Context is not an isolated environment, and if the user runs untrusted JavaScript code within the Happy DOM VM Context, it may escape the VM and get access to process level functionality.

What the attacker can get control over depends on if the process is using ESM or CommonJS. With CommonJS the attacker can get hold of the require() function to import modules.

Happy DOM has JavaScript evaluation enabled by default. This may not be obvious to the consumer of Happy DOM and can potentially put the user at risk if untrusted code is executed within the environment.

Reproduce

CommonJS (Possible to get hold of require)

const { Window } = require('happy-dom');
const window = new Window({ console });

window.document.write(`
  <script>
     const process = this.constructor.constructor('return process')();
     const require = process.mainModule.require;
  
     console.log('Files:', require('fs').readdirSync('.').slice(0,3));
  </script>
`);

ESM (Not possible to get hold of import or require)

const { Window } = require('happy-dom');
const window = new Window({ console });

window.document.write(`
  <script>
     const process = this.constructor.constructor('return process')();
  
     console.log('PID:', process.pid);
  </script>
`);

Potential Impact

Server-Side Rendering (SSR)

const { Window } = require('happy-dom');
const window = new Window();
window.document.innerHTML = userControlledHTML;

Testing Frameworks

Any test suite using Happy-DOM with untrusted content may be at risk.

Attack Scenarios

Data Exfiltration: Access to environment variables, configuration files, secrets
Lateral Movement: Network access for connecting to internal systems. Happy DOM already gives access to the network by fetch, but has protections in place (such as CORS and header validation etc.).

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CVE-2025-61927

CVE-2025-61927:

N/A

CVSS Score

-

CVSS Score

Basic Information

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Technical Details

Package Name	Ecosystem	Vulnerable Versions	First Patched Version
happy-dom	npm	< 20.0.0	20.0.0

Technical Details

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability in Happy DOM is a classic VM escape caused by the improper use of eval() within a Node.js vm context. By default, JavaScript evaluation was enabled, and several functions across the library used eval() to execute script code from various sources (inline scripts, external scripts, javascript: URLs, and event handlers).

The core of the issue is that the eval function provided within the Happy DOM window object was not properly sandboxed. Malicious JavaScript code could abuse this by walking up the constructor chain (e.g., this.constructor.constructor('return process')()) to gain access to the Function constructor of the parent Node.js process. This escape from the vm sandbox allows the attacker to access the process object, require(), and other Node.js internals, leading to Remote Code Execution (RCE).

The identified vulnerable functions are the specific locations in the codebase where these insecure eval() calls were made. During an exploit, a stack trace would likely show one of these functions calling the eval function. The patch addresses the vulnerability by replacing all instances of eval() with a new, safer method ([PropertySymbol.evaluateScript]) that uses vm.Script.runInContext(). Additionally, the patch disables JavaScript evaluation by default, making the library secure out-of-the-box and requiring developers to consciously opt-in to the potentially risky feature.

Vulnerable functions

Only Mi**o us*rs **n s** t*is s**tion

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WAF Protection Rules

WAF Rule

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Reasoning

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N/A

-

Basic Information

Basic Information

Concerned about an active attack path?

CVE-2025-61927: Happy DOM: VM Context Escape can lead to Remote Code Execution

Escape of VM Context gives access to process level functionality

Summary

Reproduce

CommonJS (Possible to get hold of require)

ESM (Not possible to get hold of import or require)

Potential Impact

Server-Side Rendering (SSR)

Testing Frameworks

Attack Scenarios

CVE-2025-61927:

N/A

-

Basic Information

Basic Information

Is this CVE running in your environment?

Technical Details

Technical Details

Vulnerability IntelligenceMiggo AI

Root Cause Analysis

Vulnerable functions

Vulnerability IntelligenceMiggo AI

Unlock WAF rules for this CVE

WAF Protection Rules

WAF Rule

Reasoning

Basic Information

Basic Information

N/A

N/A

Vulnerability IntelligenceMiggo AI

Root Cause Analysis

Vulnerable functions

Technical Details

CVE-2025-61927: Happy DOM: VM Context Escape can lead to Remote Code Execution

Escape of VM Context gives access to process level functionality

Summary

Reproduce

CommonJS (Possible to get hold of require)

ESM (Not possible to get hold of import or require)

Potential Impact

Server-Side Rendering (SSR)

Testing Frameworks

Attack Scenarios

Recommended Immediate Actions

Technical Root Cause

Vulnerability Intelligence
Miggo AI

Vulnerability Intelligence
Miggo AI

Vulnerability Intelligence
Miggo AI