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10.0

vm2 lets sandboxed code run host commands

CVE-2026-93603 · published 22 days ago
Summary

The vm2 JavaScript sandbox (versions before 3.12.1) can mistakenly give untrusted code access to the host system's global objects. If your application exposes any non‑strict host functions to the sandbox, an attacker could use them to execute commands on the server. Upgrade vm2 to version 3.12.1 or later, or stop exposing non‑strict host functions to the sandbox.

What to do
  • Update patriksimek vm2 to version 3.12.1 or later.
Affected software
VendorProductAffected versions
patriksimek vm2 < 3.12.1
Original advisory text
vm2 before 3.12.1 Sandbox Escape RCE via Non-Strict Host Function
vm2 through 3.12.0 (fixed in 3.12.1) does not correctly handle a nullish `this` receiver in the apply trap of its bridge (lib/bridge.js): when sandboxed code calls a host-provided non-strict (sloppy-mode) function without a receiver — e.g. `fn()`, a detached method, `fn.call()`, `fn.apply(undefined)`, `Reflect.apply(fn, undefined, [])`, or `fn.bind()()` — the undefined receiver is passed straight through to the host call, and V8 substitutes the host realm's global object for `this`. vm2 then wraps and returns that object to the sandbox, giving sandboxed script a live proxy of the host global. This allows a complete sandbox escape: untrusted script can reach `process` and execute arbitrary code/commands on the host (for example via `process.getBuiltinModule('child_process').execSync`). Exploitation requires that the embedding application expose at least one non-strict host function to the sandbox; strict-mode and ES module host functions are not affected.
References
Fix within
Internet-facing 3 days
Internal 60 days
  • Not known to be exploited
  • Can be exploited automatically
  • Gives an attacker full control
Severity
10.0 Critical
Exploitation
<1% chance of attack within 30 days
Type
CWE-94Code Injection
Timeline
Published18 Sep 2026
Updated9 Oct 2026
First seen18 Sep 2026
Sources
CVE-2026-93603 · NVD
CVE-2026-93603 · MITRE
CVE-2026-93603 · OSV
GHSA-j89j-5m6r-cr2q · GHSA
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