---
id: CVE-2026-107302
title: msgpack5 is a msgpack v5 implementation for node.js and the browser
summary: >-
  msgpack5 is a msgpack v5 implementation for node.js and the browser. Prior to
  6.1.0, the decoder reads the four-byte length of a map32 value before
  validating that the complete five-byte header is available. A truncated map32
  header ther…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-125
vendor: msgpack5
product: msgpack5
affected:
  - msgpack5 < 6.1.0
patched:
  - msgpack5 6.1.0
published: '2026-10-08'
updated: '2026-10-08'
sourceUpdated: '2026-10-08T20:48:36.970'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-107302'
references:
  - url: >-
      https://github.com/mcollina/msgpack5/commit/15443a1f2aa682a6aa37f1705ac628de5b866ad1
    label: security-advisories@github.com
  - url: 'https://github.com/mcollina/msgpack5/releases/tag/v6.1.0'
    label: security-advisories@github.com
  - url: >-
      https://github.com/mcollina/msgpack5/security/advisories/GHSA-8f34-f56x-9xph
    label: security-advisories@github.com
  - url: 'https://github.com/advisories/GHSA-8f34-f56x-9xph'
tags:
  - nvd
  - ghsa
  - npm
  - cve.org
aliases:
  - GHSA-8f34-f56x-9xph
ecosystem: npm
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-10-08T17:32:15.263797Z'
ingestedAt: '2026-10-08T17:56:11.724Z'
---

## Overview

msgpack5 is a msgpack v5 implementation for node.js and the browser. Prior to 6.1.0, the decoder reads the four-byte length of a map32 value before validating that the complete five-byte header is available. A truncated map32 header therefore causes a checked out-of-bounds buffer read and throws RangeError instead of IncompleteBufferError, which can unexpectedly terminate a request, stream, or worker in applications that wait for additional bytes after IncompleteBufferError. There is no adjacent-memory disclosure because the buffer implementation checks bounds. This issue is fixed in version 6.1.0.

## Remediation

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

## Package advisory (CVE-2026-107302)

Affected packages:

- `msgpack5 < 6.1.0`

Patched in:

- `msgpack5 6.1.0`

Source: https://github.com/advisories/GHSA-8f34-f56x-9xph