MEDIUM 6.5 NVD
CVE-2026-107301
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
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.
References
- https://github.com/mcollina/msgpack5/commit/20e82600ac9462e679c8a45e5723315f21e2c774
- https://github.com/mcollina/msgpack5/releases/tag/v6.1.0
- https://github.com/mcollina/msgpack5/security/advisories/GHSA-8hq7-ggx2-cc6m
This medium severity vulnerability with a CVSS score of 6.5 was published on 2026-10-08 via NVD.
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