8.6

CVSS Score

3.1

-

CVSS Score

Basic Information

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CVE-2026-44001

CVE-2026-44001: vm2: Sandbox Escape via Promise Constructor Unhandled Rejection (Process Crash DoS)

vm2 is an open source vm/sandbox for Node.js. Prior to 3.11.0, a sandbox escape vulnerability in vm2 v3.10.5 allows any sandboxed code to crash the host Node.js process via a single Promise constructor that triggers an unhandled rejection propagating to the host. The fix for CVE-2026-22709 (v3.10.2) only sanitized the onRejected callback in .then() and .catch() overrides and did not address the executor-to-unhandledRejection path. This vulnerability is fixed in 3.11.0.

(GitHub Advisory)

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CVE-2026-44001

CVE-2026-44001:

8.6

CVSS Score

3.1

-

CVSS Score

Basic Information

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Technical Details

Package Name	Ecosystem	Vulnerable Versions	First Patched Version
vm2	npm	<= 3.10.5	3.11.0

Technical Details

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability lies in the way vm2 handled Promise instantiation within the sandboxed environment. The security advisory GHSA-hw58-p9xv-2mjh and the corresponding patch make it clear that the localPromise class in lib/setup-sandbox.js was the source of the issue. Prior to the fix, localPromise was an empty extension of the host's Promise class, meaning it used the host's Promise constructor directly. This constructor did not have any mechanism to trap exceptions occurring within the executor function when called from the sandbox. As a result, a synchronous exception inside the executor would lead to an unhandled promise rejection on the host, which, by default in recent Node.js versions, terminates the process.

The patch rectifies this by implementing a custom constructor for localPromise. This new constructor wraps the sandboxed executor function in a try...catch block. If an exception is caught, it is passed to the handleException function to be safely sanitized before the promise is rejected within the sandbox's context. This prevents the exception from ever becoming an unhandled rejection on the host. The vulnerable function is therefore the Promise constructor available in the sandbox, which is localPromise.constructor.

Vulnerable functions

localPromise.constructor

lib/setup-sandbox.js

The `localPromise` class, which serves as the sandboxed version of the native `Promise`, lacked its own constructor. Consequently, it inherited the constructor from the host's `Promise` object. This allowed an uncaught exception thrown within a Promise executor in the sandbox to propagate to the host environment as an unhandled promise rejection, leading to a process crash (Denial of Service). The vulnerability is triggered when `new Promise(executor)` is called in the sandbox and the `executor` function throws an exception.

Vulnerability Intelligence
Miggo AI

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WAF Rule

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Reasoning

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