CVE-2026-92952: vm2 sandbox symbol filtering bypass in Node.js symbol isolation

CVE-2026-92952 · Severity: medium · CVSS 6.8 · Published 2026-09-17

vm2 is a popular JavaScript sandbox that isolates untrusted code from the host environment. Versions 3.11.4 through 3.11.6 fail to block certain internal Node.js stream symbols, allowing sandbox code to corrupt the state of host stream objects and bypass stream-safety checks. An attacker with code execution in the sandbox can trick the host into treating already-consumed streams as fresh, potentially bypassing security controls that rely on stream state verification.

Technologies: vm2 (npm). Vendors: npm.

Quick answers

Is CVE-2026-92952 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-92952 being exploited in the wild.
How severe is CVE-2026-92952?
Medium severity, with a CVSS score of 6.8, published 17 September 2026.
Which products and versions are affected?
vm2 (npm) >= 3.11.4, <= 3.11.6, SEMVER:introduced=3.11.4,fixed=3.11.7.
Is there a fix for CVE-2026-92952?
Yes. vm2 (npm): upgrade to 3.11.7 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-92952 attacked?
It is attacked over the network or with local access, in a software library.
Am I affected by CVE-2026-92952?
Check whether you run vm2 (npm) 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.

How to fix

  • vm2 (npm): upgrade to 3.11.7 or later
    npm install vm2@3.11.7

Technical details

vm2 uses a fixed allowlist of dangerous registered Node.js symbols (e.g. nodejs.util.inspect.custom) to prevent sandbox code from accessing host internals across the sandbox boundary. However, this allowlist in lib/setup-sandbox.js and lib/bridge.js omits two newer symbols exposed in Node.js v25.8.0+: nodejs.stream.disturbed and nodejs.stream.errored. Sandbox code can extract these real host symbols via Object.getOwnPropertySymbols(streamWeb.ReadableStream.prototype) and write them as own properties on host stream objects, corrupting their internal state. The attack requires the embedder to expose a host WebStream object and the stream/web module to the sandbox. While not a direct code execution primitive, this breaks stream state verification and can bypass host logic that enforces one-shot stream consumption or rejects unsafe streams. Fixed in vm2 3.11.7.

Affected products

  • patriksimek vm2 3.11.4 through 3.11.6

Identifiers

  • CVE-2026-92952
  • GHSA-jf8q-945g-9q4c

Timeline

  • 2026-08-24: disclosed: GitHub Security Advisory GHSA-jf8q-945g-9q4c published
  • 2026-09-17: advisory: CVE-2026-92952 assigned; NVD and VulnCheck published
  • 2026-09-17: patched: vm2 3.11.7 released with fix

References

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.