MCP Registry: OCI ownership validation fails open on upstream rate limits, allowing attacker-controlled package claims

{
  "id": "1956ba31186700cc1c70f458ecb36704630c0e0a0fd2d31e7244c652868d56f2",
  "url": "https://osv.dev/vulnerability/CVE-2026-45781",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "MCP Registry: OCI ownership validation fails open on upstream rate limits, allowing attacker-controlled package claims",
    "summary": "The MCP Registry provides MCP clients with a list of MCP servers, like an app store for MCP servers. Prior to 1.7.9, OCI ownership validation skips label-match check when upstream OCI registry returns HTTP 429, letting any authenticated publisher bind their io.github./* namespace to OCI images they do not control. internal/validators/registries/oci.go:104-119 fails open on http.StatusTooManyRequests: when the registry's anonymous fetch to the upstream OCI registry is rate-limited, ValidateOCI returns nil and the publish is accepted without ever running the io.modelcontextprotocol.server.name label-match check at lines 122-141. That label check is the only cross-system ownership proof the registry applies to OCI packages — every other registry type (NPM, PyPI, NuGet, MCPB) treats a non-200 upstream response as a hard error. This vulnerability is fixed in 1.7.9.",
    "evidence": "osv:CVE-2026-45781",
    "products": [],
    "severity": "low",
    "structured": {
      "id": "CVE-2026-45781",
      "aliases": [
        "CVE-2026-45781",
        "GHSA-2v5f-5r6w-p67r",
        "GO-2026-5008"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/modelcontextprotocol/registry",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "35b20719ee7714ad18d0f81af6798ac0a46e2b9b"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "1.7.9"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "1.7.9"
                      }
                    ],
                    "source": "DESCRIPTION"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v1.7.8",
            "v1.7.7",
            "v1.7.6",
            "v1.7.5",
            "v1.7.4",
            "v1.7.3",
            "v1.7.2",
            "v1.7.1",
            "v1.7.0",
            "v1.6.0",
            "v1.5.0",
            "v1.4.1",
            "v1.4.0",
            "v1.3.10",
            "v1.3.9",
            "v1.3.8",
            "v1.3.7",
            "v1.3.6",
            "v1.3.5",
            "v1.3.4",
            "v1.3.3",
            "v1.3.2",
            "v1.3.1",
            "v1.3.0",
            "v1.2.3",
            "v1.2.2",
            "v1.2.1",
            "v1.2.0",
            "v1.1.0",
            "v1.0.0",
            "v0.0.3",
            "v0.0.2",
            "v0.0.1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-45781.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:36.391765844Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45781.json",
        "https://github.com/modelcontextprotocol/registry/security/advisories/GHSA-2v5f-5r6w-p67r",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-45781"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-636"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45781.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-45781",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 503817,
  "published_at": "2026-05-14T21:00:49.961+00:00"
}