---
id: CVE-2026-100723
title: >-
  vm2 before 3.12.2 does not apply its Buffer backing-store ownership invariant
  (byteOffset === 0 and buffer.byteLength === length) to Buffers returned from
  host builtin modules
summary: >-
  vm2 before 3.12.2 does not apply its Buffer backing-store ownership invariant
  (byteOffset === 0 and buffer.byteLength === length) to Buffers returned from
  host builtin modules. When an application explicitly exposes Node's zlib
  module th…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:L/A:N'
cwe:
  - CWE-200
vendor: patriksimek
product: vm2
affected:
  - vm2 < 3.12.2
published: '2026-09-27'
updated: '2026-09-27'
sourceUpdated: '2026-09-27T02:17:20.553'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-100723'
references:
  - url: >-
      https://github.com/patriksimek/vm2/commit/4f2508abeb252aa86eb6761c78b3b000248fb089
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/patriksimek/vm2/commit/5214b02ef13b82497fcb917b45320dfd014ffd09
    label: disclosure@vulncheck.com
  - url: 'https://github.com/patriksimek/vm2/security/advisories/GHSA-489w-w794-jq94'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/vm2-before-3.12.2-memory-disclosure-via-zlib-buffer-pool
    label: disclosure@vulncheck.com
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-27T02:41:45.566Z'
---

## Overview

vm2 before 3.12.2 does not apply its Buffer backing-store ownership invariant (byteOffset === 0 and buffer.byteLength === length) to Buffers returned from host builtin modules. When an application explicitly exposes Node's zlib module through NodeVM's builtin allowlist (require: { builtin: ['zlib'] }), zlib.deflateSync can return a Buffer backed by Node's shared small-buffer pool whose .buffer is the entire pool. Untrusted guest code can construct a full-width view of that ArrayBuffer (Buffer.from(result.buffer, 0, result.buffer.byteLength)) to read and modify bytes belonging to unrelated host buffers, disclosing and corrupting host-realm memory across the sandbox boundary.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.