CVE-2026-107301 — msgpack5: Partial options disable prototype protection
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 protoActi…
Published: 2026-10-08 · CVSS: 6.5 · CVSS 3.1
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: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7