msgpack5: Partial options disable prototype protection

{
  "id": "d8d5c64a208c137ac271be116a5a6acb4d43f1c916038d5e83d232c37fe04ed8",
  "url": "https://osv.dev/vulnerability/GHSA-8hq7-ggx2-cc6m",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "msgpack5: Partial options disable prototype protection",
    "summary": "### Impact Passing an empty or partial options object disables the default `protoAction: 'error'` protection. A map containing a `__proto__` key can then replace the prototype of the decoded object, potentially changing inherited properties or causing unexpected behavior in downstream code. Only the decoded object's prototype is affected; this does not modify `Object.prototype` globally. ### Patches Options are now merged with secure defaults without modifying the caller's object. Unsupported `protoAction` values are rejected. ### Workarounds Explicitly set `protoAction: 'error'` whenever constructing a msgpack5 instance, and validate decoded values before use.",
    "evidence": "osv:GHSA-8hq7-ggx2-cc6m",
    "products": [
      {
        "name": {
          "value": "msgpack5",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.1.0",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "GHSA-8hq7-ggx2-cc6m",
      "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": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "6.1.0"
                }
              ]
            }
          ],
          "package": {
            "name": "msgpack5",
            "purl": "pkg:npm/msgpack5",
            "ecosystem": "npm"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-8hq7-ggx2-cc6m/GHSA-8hq7-ggx2-cc6m.json"
          }
        }
      ],
      "modified": "2026-10-08T18:00:08.899286917Z",
      "provider": "osv",
      "references": [
        "https://github.com/mcollina/msgpack5/security/advisories/GHSA-8hq7-ggx2-cc6m",
        "https://github.com/mcollina/msgpack5/commit/20e82600ac9462e679c8a45e5723315f21e2c774",
        "https://github.com/mcollina/msgpack5",
        "https://github.com/mcollina/msgpack5/releases/tag/v6.1.0"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-1321"
        ],
        "severity": "MODERATE",
        "github_reviewed": true,
        "nvd_published_at": null,
        "github_reviewed_at": "2026-10-08T17:39:57Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-107301",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 104430,
  "published_at": "2026-10-08T17:39:57+00:00"
}