Disclosure summary
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.
Source-reported weakness categories
CWE-1321
Source-specific records & product guidance
Sources retain their own attribution and scoring. Follow the original record to confirm affected versions, fixed releases, and configuration conditions.
NIST National Vulnerability Database · NVD-CVE-2026-107301
Open original source · Updated Oct 08, 2026
Only CPE matches marked vulnerable=true are indexed. AND/OR platform conditions must be checked in the original NVD record.
GitHub Reviewed Security Advisories · GHSA-8hq7-ggx2-cc6m
Open original source · Updated Oct 08, 2026
msgpack5: Partial options disable prototype protection
Source severity: MEDIUM / 0
| Ecosystem | Package | Affected range | First patched |
|---|---|---|---|
| npm | msgpack5 | < 6.1.0 | 6.1.0 |
Original records & references
PUBLISHED 2026-10-08T13:17:16-04:00
MODIFIED 2026-10-08T16:48:36-04:00
INGESTED 2026-10-10T20:55:03-04:00