CVE-2026-44006 Overview
CVE-2026-44006 is a sandbox escape vulnerability in vm2, an open source virtual machine and sandbox library for Node.js. Versions prior to 3.11.0 allow code running inside the sandbox to reach BaseHandler.getPrototypeOf, which can be used to obtain arbitrary prototypes from the host context. An attacker who controls code executed inside the sandbox can leverage this prototype access to break out and execute code with the privileges of the host Node.js process.
Critical Impact
Attackers can escape the vm2 sandbox and achieve arbitrary code execution on the host with full confidentiality, integrity, and availability impact.
Affected Products
- vm2 versions prior to 3.11.0
- Node.js applications embedding vm2 for untrusted code execution
- Services using vm2 to evaluate user-supplied scripts or expressions
Discovery Timeline
- 2026-05-13 - CVE-2026-44006 published to NVD
- 2026-05-14 - Last updated in NVD database
Technical Details for CVE-2026-44006
Vulnerability Analysis
The vm2 library implements a JavaScript sandbox by wrapping host objects in Proxy handlers that mediate access between sandbox code and the host runtime. These handlers are designed to block access to host internals, including object prototypes that could expose constructors leading to the host Function or process objects.
In versions before 3.11.0, sandboxed code can reach the getPrototypeOf trap on BaseHandler. The trap returns prototypes from the host realm rather than the sandboxed realm. Once an attacker obtains a host prototype, they can walk the prototype chain to reach Function.prototype.constructor and instantiate a function that executes in the host context. This breaks the isolation contract that vm2 provides and converts untrusted in-sandbox code into full host code execution.
The issue is categorized under [CWE-94] Improper Control of Generation of Code. It is exploitable over the network whenever an application exposes vm2 to untrusted input, with no authentication or user interaction required.
Root Cause
The root cause is incomplete mediation in the proxy handler logic. BaseHandler.getPrototypeOf does not consistently return a sandbox-safe prototype, allowing host objects to leak across the trust boundary established by the sandbox.
Attack Vector
Exploitation requires the attacker to submit JavaScript that the application evaluates inside a vm2NodeVM or VM instance. The attacker triggers a getPrototypeOf operation, for example through Object.getPrototypeOf or Reflect.getPrototypeOf on a proxied host object, then walks the returned prototype chain to reach a host constructor and execute arbitrary code outside the sandbox.
No verified public proof-of-concept is referenced in the advisory. For technical details, see the GitHub Security Advisory GHSA-qcp4-v2jj-fjx8.
Detection Methods for CVE-2026-44006
Indicators of Compromise
- Unexpected child processes spawned by Node.js services that embed vm2, particularly shells or network utilities.
- Outbound network connections initiated by Node.js worker processes evaluating untrusted scripts.
- File system writes or reads outside the application working directory by processes hosting vm2.
Detection Strategies
- Inventory all Node.js applications and identify dependencies on vm2 below version 3.11.0 using software composition analysis.
- Inspect application logs for sandbox evaluation errors referencing getPrototypeOf, Proxy, or unexpected constructor access.
- Hunt for runtime anomalies where a Node.js process executing vm2 deviates from its baseline syscall or process-spawn behavior.
Monitoring Recommendations
- Alert on new process creation by Node.js services that historically do not spawn children.
- Monitor egress traffic from sandboxed evaluation services for connections to untrusted destinations.
- Track package manifests in CI for vm2 versions and fail builds that pin a vulnerable release.
How to Mitigate CVE-2026-44006
Immediate Actions Required
- Upgrade vm2 to version 3.11.0 or later in all Node.js applications.
- Audit application code paths that pass untrusted input to vm2.run, NodeVM.run, or equivalent APIs.
- Rotate any secrets accessible to the Node.js process if exploitation is suspected.
Patch Information
The maintainers fixed the issue in vm2 3.11.0 by correcting the BaseHandler.getPrototypeOf behavior so that host prototypes are not returned to sandboxed code. Refer to the GitHub Security Advisory GHSA-qcp4-v2jj-fjx8 for the official fix details.
Workarounds
- If immediate upgrade is not possible, stop accepting untrusted JavaScript for evaluation in vm2.
- Migrate to a maintained sandbox alternative such as isolated-vm that uses V8 isolates for stronger boundary enforcement.
- Run the Node.js process under a restrictive OS sandbox, container, or seccomp profile to limit impact of a successful escape.
# Upgrade vm2 to the patched version
npm install vm2@^3.11.0
npm audit --production
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
