msgpack5 is a msgpack v5 implementation for node.js and the browser. Prior to 6.1.0, constructing msgpack5 with an empty or partial options object disables the default protoAction: 'error' protection. A decoded map containing a __proto__ key can then replace the decoded object's prototype, potentially changing inherited properties or downstream behavior, although Object.prototype is not modified globally. This issue is fixed in version 6.1.0.
History

Wed, 14 Oct 2026 01:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Fri, 09 Oct 2026 09:15:00 +0000

Type Values Removed Values Added
First Time appeared Mcollina
Mcollina msgpack5
Vendors & Products Mcollina
Mcollina msgpack5

Thu, 08 Oct 2026 17:15:00 +0000

Type Values Removed Values Added
Description msgpack5 is a msgpack v5 implementation for node.js and the browser. Prior to 6.1.0, constructing msgpack5 with an empty or partial options object disables the default protoAction: 'error' protection. A decoded map containing a __proto__ key can then replace the decoded object's prototype, potentially changing inherited properties or downstream behavior, although Object.prototype is not modified globally. This issue is fixed in version 6.1.0.
Title msgpack5: Partial options disable prototype protection
Weaknesses CWE-1321
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:L'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published: 2026-10-08T17:13:00.613Z

Updated: 2026-10-14T01:02:53.277Z

Reserved: 2026-10-07T15:53:23.587Z

Link: CVE-2026-107301

cve-icon Vulnrichment

Updated: 2026-10-14T01:02:48.909Z

cve-icon NVD

Status : Deferred

Published: 2026-10-08T17:17:16.143

Modified: 2026-10-14T01:17:05.583

Link: CVE-2026-107301

cve-icon Redhat

No data.