CVE-2026-107301 affecting package msgpack 3.3.0-1

{
  "id": "655866340a11939ecdfa2b54464fd2d4ec1b0bdab23814b430de45cd30e6227e",
  "url": "https://osv.dev/vulnerability/AZL-106857",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2026-107301 affecting package msgpack 3.3.0-1",
    "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:AZL-106857",
    "products": [
      {
        "name": {
          "value": "msgpack",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "AZL-106857",
      "aliases": [
        "AZL-106857"
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "last_affected": "3.3.0-1"
                }
              ]
            }
          ],
          "package": {
            "name": "msgpack",
            "purl": "pkg:rpm/azure-linux/msgpack",
            "ecosystem": "Azure Linux:3"
          },
          "database_specific": {
            "source": "https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-106857.json"
          }
        }
      ],
      "modified": "2026-10-15T05:37:09Z",
      "provider": "osv",
      "upstream": [
        "CVE-2026-107301"
      ],
      "references": [
        "https://nvd.nist.gov/vuln/detail/CVE-2026-107301"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2026-107301",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 321455,
  "published_at": "2026-10-08T17:17:16+00:00"
}