msgpack5: Partial options disable prototype protection

{
  "id": "345213d3403deb72476bd7b7e5af35a02a74d263d4364ba185af5b013a7c478a",
  "url": "https://osv.dev/vulnerability/CVE-2026-107301",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "msgpack5: Partial options disable prototype protection",
    "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.",
    "evidence": "osv:CVE-2026-107301",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-107301",
      "aliases": [
        "CVE-2026-107301",
        "GHSA-8hq7-ggx2-cc6m"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:L"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/mcollina/msgpack5",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "3730a5a754ec06912e42865eed9489ed64238ecb"
                },
                {
                  "fixed": "20e82600ac9462e679c8a45e5723315f21e2c774"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "6.1.0"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "fixed": "20e82600ac9462e679c8a45e5723315f21e2c774"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "3730a5a754ec06912e42865eed9489ed64238ecb"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v6.1.0"
                  }
                ]
              }
            }
          ],
          "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"
          }
        }
      ],
      "modified": "2026-10-28T02:30:24.177773130Z",
      "provider": "osv",
      "references": [
        "https://github.com/mcollina/msgpack5/releases/tag/v6.1.0",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/107xxx/CVE-2026-107301.json",
        "https://github.com/mcollina/msgpack5/security/advisories/GHSA-8hq7-ggx2-cc6m",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-107301",
        "https://github.com/mcollina/msgpack5/commit/20e82600ac9462e679c8a45e5723315f21e2c774"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-1321"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/107xxx/CVE-2026-107301.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-107301",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 490513,
  "published_at": "2026-10-08T17:13:00.613+00:00"
}