---
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
  - CWE-653
  - CWE-787
vendor: patriksimek
product: vm2
affected:
  - vm2 < 3.12.2
published: '2026-09-27'
updated: '2026-10-01'
sourceUpdated: '2026-10-01T19:17:16.563'
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
  - url: 'https://github.com/patriksimek/vm2/security/advisories/GHSA-489w-w794-jq94'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-100723.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-100723'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2542016'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-100723'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-100723'
  - url: >-
      https://github.com/patriksimek/vm2/commit/9596bf5e7d8de7351d675ff4f5293b72157202d4
  - url: 'https://github.com/patriksimek/vm2/releases/tag/v3.12.2'
  - url: 'https://github.com/advisories/GHSA-489w-w794-jq94'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
  - exploit-available
  - ghsa
  - npm
  - score-dispute
epss: 0.00392
epssPercentile: 0.33118
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-01T18:04:51.057802Z'
ingestedAt: '2026-09-27T02:41:45.566Z'
aliases:
  - GHSA-489w-w794-jq94
ecosystem: npm
patched:
  - vm2 3.12.2
scores:
  nvd: 7.5
  ghsa: 10
---

## 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.

## Vendor advisories

- **Red Hat VEX** · Important · updated 2026-09-28 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-100723.json)

## Package advisory (CVE-2026-100723)

Affected packages:

- `vm2 <= 3.12.1`

Patched in:

- `vm2 3.12.2`

Source: https://github.com/advisories/GHSA-489w-w794-jq94