{"id":"CVE-2026-107301","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, constructing msgpack5 with an empty or partial options object disables the default protoAction: 'error' protection. A decoded map containing a __proto__…","severity":"medium","cvss":6.5,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:L","cwe":["CWE-1321"],"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-2026-107301","references":[{"url":"https://github.com/mcollina/msgpack5/commit/20e82600ac9462e679c8a45e5723315f21e2c774","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-8hq7-ggx2-cc6m","label":"security-advisories@github.com"},{"url":"https://github.com/advisories/GHSA-8hq7-ggx2-cc6m"}],"tags":["nvd","ghsa","npm","cve.org"],"aliases":["GHSA-8hq7-ggx2-cc6m"],"ecosystem":"npm","ingestedAt":"2026-10-08T17:56:11.716Z","slug":"CVE-2026-107301","body":"## Overview\n\nmsgpack5 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Package advisory (CVE-2026-107301)\n\nAffected packages:\n\n- `msgpack5 < 6.1.0`\n\nPatched in:\n\n- `msgpack5 6.1.0`\n\nSource: https://github.com/advisories/GHSA-8hq7-ggx2-cc6m","depth":"sunlit","depthScore":36,"depthScoreParts":{"impact":35.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}