{
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      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-123272",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-11-05T21:01:43.498683Z",
                "version": "2.0.3"
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          "dateUpdated": "2026-11-05T21:01:52.297Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "packageURL": "pkg:golang/github.com/mark3labs/mcp-go",
          "product": "mcp-go",
          "repo": "https://github.com/mark3labs/mcp-go",
          "vendor": "mark3labs",
          "versions": [
            {
              "lessThan": "v1.2.1",
              "status": "affected",
              "version": "v0.48.0",
              "versionType": "semver"
            }
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        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Theodoros Lampropoulos"
        },
        {
          "lang": "en",
          "type": "remediation developer",
          "value": "Ed Zynda (ezynda3)"
        }
      ],
      "datePublic": "2026-10-09T00:00:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "value": "Mark3labs mcp-go before v1.2.1 contains an improper validation vulnerability in OAuthHandler.fetchServerMetadata that allows malicious MCP servers to obtain tokens for other resources by declaring arbitrary resources in well-known metadata. Attackers can declare a different MCP server as the RFC 8707 resource indicator, causing the authorization server to mint tokens the attacker replays against that resource."
        }
      ],
      "metrics": [
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            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 5.1,
            "baseSeverity": "MEDIUM",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "HIGH",
            "subIntegrityImpact": "HIGH",
            "userInteraction": "ACTIVE",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE"
          },
          "format": "CVSS"
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            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "CHANGED",
            "userInteraction": "REQUIRED",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N",
            "version": "3.1"
          },
          "format": "CVSS"
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      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-346",
              "description": "Origin Validation Error",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
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      "providerMetadata": {
        "dateUpdated": "2026-11-05T18:45:36.197Z",
        "orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
        "shortName": "VulnCheck"
      },
      "references": [
        {
          "name": "GitHub Security Advisory (GHSA-xf6j-693p-wqxx)",
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://github.com/mark3labs/mcp-go/security/advisories/GHSA-xf6j-693p-wqxx"
        },
        {
          "tags": [
            "issue-tracking",
            "patch"
          ],
          "url": "https://github.com/mark3labs/mcp-go/pull/1053"
        },
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/mark3labs/mcp-go/commit/90d247ed8d45cbb7d71d9a95e112789b78760443"
        },
        {
          "name": "mcp-go v1.2.1 Release Notes",
          "tags": [
            "release-notes"
          ],
          "url": "https://github.com/mark3labs/mcp-go/releases/tag/v1.2.1"
        },
        {
          "tags": [
            "technical-description"
          ],
          "url": "https://github.com/mark3labs/mcp-go/blob/4cb0d2015f24b669726fd8e5e53fc8c6d3f57abf/client/transport/oauth.go#L799-L821"
        },
        {
          "name": "VulnCheck Advisory: mcp-go before v1.2.1 Origin Validation Error via Unvalidated Well-Known Protected Resource Metadata",
          "tags": [
            "third-party-advisory"
          ],
          "url": "https://www.vulncheck.com/advisories/mcp-go-before-1.2.1-origin-validation-error-via-unvalidated-well-known-protected-resource-metadata"
        }
      ],
      "title": "mcp-go before v1.2.1 Origin Validation Error via Unvalidated Well-Known Protected Resource Metadata",
      "x_generator": {
        "engine": "vulncheck-endgame"
      }
    }
  },
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    "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
    "assignerShortName": "VulnCheck",
    "cveId": "CVE-2026-123272",
    "datePublished": "2026-11-05T18:45:36.197Z",
    "dateReserved": "2026-11-05T18:19:12.668Z",
    "dateUpdated": "2026-11-05T21:01:52.297Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}