---
id: CVE-2026-92959
title: >-
  vm2 before 3.11.8 does not fully enforce the allowAsync: false option in VM
  and NodeVM
summary: >-
  vm2 before 3.11.8 does not fully enforce the allowAsync: false option in VM
  and NodeVM. While localPromise.prototype.then is replaced with a handler that
  throws 'Async not available', the sandbox's Promise static methods
  (Promise.resolve…
severity: high
cvss: 7.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H'
cwe:
  - CWE-693
  - CWE-358
vendor: patriksimek
product: vm2
affected:
  - vm2 < 3.11.8
published: '2026-09-17'
updated: '2026-09-21'
sourceUpdated: '2026-09-21T21:17:16.917'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-92959'
references:
  - url: 'https://github.com/patriksimek/vm2/security/advisories/GHSA-f8gf-w286-fmq2'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/vm2-before-3.11.8-allowasync-bypass-via-promise-thenable
    label: disclosure@vulncheck.com
  - url: 'https://github.com/patriksimek/vm2/security/advisories/GHSA-f8gf-w286-fmq2'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-92959.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-92959'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-92959'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-92959'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2536043'
tags:
  - nvd
  - cve.org
  - exploit-available
  - csaf
  - vex
  - red-hat
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-21T20:41:04.607286Z'
epss: 0.00256
epssPercentile: 0.17577
ingestedAt: '2026-09-17T14:19:30.991Z'
---

## Overview

vm2 before 3.11.8 does not fully enforce the allowAsync: false option in VM and NodeVM. While localPromise.prototype.then is replaced with a handler that throws 'Async not available', the sandbox's Promise static methods (Promise.resolve, Promise.all, Promise.race, Promise.any, and Promise.allSettled) still assimilate attacker-supplied thenables: native promise resolution performs PromiseResolveThenableJob and invokes the sandboxed code's then method in a microtask without passing through the patched then, so the async restriction is never applied. As a result, sandboxed script can schedule work that runs after VM.run() or NodeVM.run() has returned and outside the configured timeout, continuing to execute after the host believes execution is complete.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · Important · affected: Red Hat Developer Hub, Self-service automation portal 2 · no fix planned: Red Hat Developer Hub, Self-service automation portal 2 · updated 2026-09-18 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-92959.json)