{"id":"CVE-2026-107301","summary":"msgpack5: Partial options disable prototype protection","details":"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.","aliases":["GHSA-8hq7-ggx2-cc6m"],"modified":"2026-10-09T02:49:21.313127946Z","published":"2026-10-08T17:13:00.613Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/107xxx/CVE-2026-107301.json","cna_assigner":"GitHub_M","cwe_ids":["CWE-1321"]},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/107xxx/CVE-2026-107301.json"},{"type":"FIX","url":"https://github.com/mcollina/msgpack5/commit/20e82600ac9462e679c8a45e5723315f21e2c774"},{"type":"WEB","url":"https://github.com/mcollina/msgpack5/releases/tag/v6.1.0"},{"type":"ADVISORY","url":"https://github.com/mcollina/msgpack5/security/advisories/GHSA-8hq7-ggx2-cc6m"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-107301"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/mcollina/msgpack5","events":[{"introduced":"0"},{"fixed":"3730a5a754ec06912e42865eed9489ed64238ecb"}],"database_specific":{"source":"AFFECTED_FIELD","extracted_events":[{"introduced":"0"},{"fixed":"6.1.0"}]}}],"versions":["v6.0.2","v6.0.0","v5.3.2","v5.3.1","v3.6.1","v3.6.0","v5.3.0","v5.2.1","v5.2.0","v5.1.0","v5.0.0","v4.4.0","v4.3.0","v4.2.0","v4.1.0","v4.0.2","v4.0.1","v4.0.0","v3.5.0","v3.4.1","v3.4.0","v3.3.0","v3.2.0","v3.1.0","v3.0.0","v2.3.1","v2.3.0","v2.2.0","v2.1.0","v2.0.0","v1.6.0","v1.5.0","v1.3.2","v1.3.1","v1.2.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-107301.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:L"}]}