---
id: CVE-2026-88351
title: >-
  An integer overflow vulnerability exists in the MPack Node API in MPack 1.1.1
  on 32-bit platforms
summary: >-
  An integer overflow vulnerability exists in the MPack Node API in MPack 1.1.1
  on 32-bit platforms. When parsing a specially crafted MessagePack array32 or
  map32 object with an excessively large element count, the page allocation size
  cal…
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-190
published: '2026-09-24'
updated: '2026-09-25'
sourceUpdated: '2026-09-25T18:17:31.257'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-88351'
references:
  - url: >-
      https://github.com/ludocode/mpack/commit/3d54d1215bdb5478d3ddecaf85884c58b382cd9b
    label: cve@mitre.org
  - url: 'https://github.com/ludocode/mpack/issues/123'
    label: cve@mitre.org
  - url: 'https://github.com/ludocode/mpack/issues/123'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
  - cve.org
  - exploit-available
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'yes'
  technicalImpact: total
  timestamp: '2026-09-25T18:09:19.298466Z'
ingestedAt: '2026-09-24T15:45:56.648Z'
epss: 0.00145
epssPercentile: 0.03088
---

## Overview

An integer overflow vulnerability exists in the MPack Node API in MPack 1.1.1 on 32-bit platforms. When parsing a specially crafted MessagePack array32 or map32 object with an excessively large element count, the page allocation size calculation in mpack_tree_parse_children() can overflow size_t and produce an undersized allocation. Subsequent parsing writes mpack_node_data_t records beyond the allocated heap buffer, resulting in heap-buffer-overflow, memory corruption, and denial of service.

## Remediation

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