vm2 sandbox escape via JSPI-backed Promise .finally() species bypass

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

9.8 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

• CVE-2026-47210: 1.72% estimated exploitation activity in the next 30 days; percentile 77.45 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary A sandbox escape vulnerability in vm2 allows arbitrary code execution in the host process when untrusted code is executed with async support on runtimes exposing WebAssembly JSPI (WebAssembly.promising / WebAssembly.Suspending). In the tested configuration, a JSPI-backed Promise can reach Promise.prototype.finally() in a way that bypasses the expected Promise-species hardening and exposes a host-originated rejection object to attacker-controlled species logic, breaking the sandbox boundary. This is a critical sandbox escape: any application that treats vm2 as a security boundary may be fully compromised. Details On node26, JSPI-backed Promises created through WebAssembly.promising(...) do not behave like ordinary sandbox Promises. That path yields a host-originated TypeError during JSPI processing. Inside attacker-controlled species logic reached through .finally(), the rejection object exposes a usable host constructor chain. In the tested environment, the rejection object's…

Published by the source

29 May 2026, 17:51 UTC

Last modified by the source

12 Jun 2026, 21:00 UTC

Source last checked

26 Oct 2026, 12:55 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-6j2x-vhqr-qr7q

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-6j2x-vhqr-qr7q

3. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-6j2x-vhqr-qr7q

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-47210

Advisory: vm2 sandbox escape via JSPI-backed Promise `.finally()` species bypass
IDs: CVE-2026-47210, GHSA-6j2x-vhqr-qr7q
Record: https://patchnext.com/advisories/cve-2026-47210 (revision 3, source checked 26 Oct 2026, 12:55 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: vm2 3.11.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm vm2: affected <= 3.11.3; fixed in 3.11.4

## Suggested inspection (read-only)
- `npm ls vm2 --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on vm2.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-6j2x-vhqr-qr7q (GitHub-reviewed advisory GHSA-6j2x-vhqr-qr7q lists affected ranges: npm vm2 >=0 <=3.11.3)
- Verified: https://osv.dev/vulnerability/GHSA-6j2x-vhqr-qr7q (OSV record GHSA-6j2x-vhqr-qr7q lists affected ranges: npm vm2 >=0 <3.11.4 (fixed))

Commands are suggestions: review each one before running it.