---
title: "CVE-2026-44005: vm2: Mutable Proxies for Host Intrinsic Prototypes Allows Sandbox Escape"
url: https://erroneo.us/security/cve/CVE-2026-44005/
description: "CVE-2026-44005 (vm2 (npm)): vm2 is an open source vm/sandbox for Node.js. From 3.9.6 to 3.10.5, vm2's bridge exposes mutable proxies for real host-realm…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-05-13
date_modified: 2026-09-07
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-44005"
kev: false
cvss: 10
epss: 0.00828
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-44005: vm2: Mutable Proxies for Host Intrinsic Prototypes Allows Sandbox Escape

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.8% , percentile 57: FIRST’s model estimates a 0.8% chance of exploitation activity in the next 30 days, higher than 57% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes vm2 (npm) >= 3.9.6, <= 3.10.5, fixed in 3.11.0 . Check your lockfile, including transitive dependencies.

## What it is

vm2 is an open source vm/sandbox for Node.js. From 3.9.6 to 3.10.5, vm2's bridge exposes mutable proxies for real host-realm intrinsic prototypes and then forwards sandbox writes into the underlying host objects with otherReflectSet() and otherReflectDefineProperty(), which lets attacker-controlled JavaScript running in a default VM or inherited NodeVM mutate shared host Object.prototype, Array.prototype, and Function.prototype from inside the sandbox This vulnerability is fixed in 3.11.0.

## Affected packages

- npm `vm2` >= 3.9.6, <= 3.10.5 → fixed: 3.11.0

## Affected products (CVE record)

- patriksimek vm2: >= 3.9.6, < 3.11.0

## Severity

- GitHub_M CVSS 3.1: 10 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:H`
- redhat-SADP CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`
- GitHub CVSS 3.1: 10.0 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.83% probability of exploitation activity in the next 30 days; percentile 57.

## Sources

- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:50850)
- [GitHub Advisory GHSA-vwrp-x96c-mhwq](https://github.com/advisories/GHSA-vwrp-x96c-mhwq)
- [CVE.org record CVE-2026-44005](https://www.cve.org/CVERecord?id=CVE-2026-44005)
- [NVD entry CVE-2026-44005](https://nvd.nist.gov/vuln/detail/CVE-2026-44005)
- [github.com](https://github.com/patriksimek/vm2/security/advisories/GHSA-vwrp-x96c-mhwq)
- [access.redhat.com](https://access.redhat.com/security/cve/CVE-2026-44005)
- [RHBZ#2477205](https://bugzilla.redhat.com/show_bug.cgi?id=2477205)
- [security.access.redhat.com](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-44005.json)
- [github.com](https://github.com/patriksimek/vm2/releases/tag/v3.11.0)

---
Source page: https://erroneo.us/security/cve/CVE-2026-44005/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt