Vulnerability · Published Sep 18, 2026 · Assigned by VulnCheck
CVE-2026-93603vm2 before 3.12.1 Sandbox Escape RCE via Non-Strict Host Function
Critical 10.0
In plain English
A critical-severity code injection in vm2 from patriksimek. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 54% of all known vulnerabilities).
Official description
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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| patriksimek | vm2 | 0 – before 3.12.1 |
Weakness: CWE-94 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
References
- GitHub Security Advisory (GHSA-j89j-5m6r-cr2q) vendor-advisory
- VulnCheck Advisory: vm2 before 3.12.1 Sandbox Escape RCE via Non-Strict Host Function third-party-advisory