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.

It seems like 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

1. Data Exfiltration: Access to environment variables, configuration files, secrets
2. 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.).
3. Code Execution: Child process access for running arbitrary commands
4. Persistence: File system access

Recommended Immediate Actions

1. Update Happy DOM to v20 or above
   • This version has JavaScript evaluation disabled by default