# vm2 sandbox escape in Promise rejection handler via call/apply indirection

Source: https://junglewise.ai/threats/duplicate-advisory-vm2-ghsa-m283-3h24-438v-fix-bypass-leads-to-host-rce-d5df51b0  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-17. Updated: 2026-10-01  
License: CC BY 4.0 with a link back

Severity: critical · CVSS 10 · Published 2026-09-17

vm2 is a JavaScript sandbox that isolates untrusted code from the host system. A flaw in version 3.11.6 allows attackers who can execute code within the sandbox to escape it and execute arbitrary commands on the host system with full process privileges by exploiting how Promise rejection handlers are sanitized. This enables complete compromise of applications using vm2 to run third-party scripts.

Technologies: [vm2 (npm)](https://junglewise.ai/threats/technologies/vm2), [Patrik Simek Vm2](https://junglewise.ai/threats/technologies/patrik-simek-vm2). Vendors: [npm](https://junglewise.ai/threats/vendors/npm), [Patrik Simek](https://junglewise.ai/threats/vendors/patrik-simek).

## Quick answers

**Is This vulnerability exploited in the wild?** No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.

**How severe is This vulnerability?** Critical severity, with a CVSS score of 10, published 17 September 2026.

**Which products and versions are affected?** vm2 (npm) = 3.11.6; Patrik Simek Vm2 3.11.6.

**Is there a fix for This vulnerability?** A patch was published on 2026: Fixed in vm2 3.11.7 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is This vulnerability attacked?** It is attacked over the network, in a software library.

**Am I affected?** Check whether you run vm2 (npm) or Patrik Simek Vm2 at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability is a sandbox escape in vm2's bridge gate (lib/bridge.js:1624) that sanitizes rejected host Promise values. The identity check only validates the direct call target, allowing attackers to use Function.prototype.call or .apply indirection to bypass sanitization. By invoking a rejection handler through p.then.call(p, undefined, cb) instead of direct p.then(undefined, cb), the intercepted target becomes Function.prototype.call rather than the original handler, preventing the sanitizer from running. An attacker can then access host objects exposed as Promise properties (e.g., err.detail.mainModule.require('child_process')) and execute arbitrary code.

## Affected products

- Patrik Simek vm2 3.11.6

## Timeline

- 2026-09-17: disclosed: Advisory published on GitHub Advisory Database
- 2026: patched: Fixed in vm2 3.11.7
- 2026-10-01: other: Advisory withdrawn as duplicate of GHSA-647f-g98j-qq25

## References

- [https://api.github.com/users/portyu9](https://api.github.com/users/portyu9)

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- [vm2 sandbox escape via Buffer backing-store ownership bypass](https://junglewise.ai/threats/cve-2026-100723-vm2-before-3-12-2-does-not-apply-its-buffer-backing-store)
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