{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "1.5.0"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "96a78eaa5c6c4bc51cced557d83d1a03344cb03d"
            },
            {
              "fixed": "c1740dc4fd6a10e42f771b2c7715d2e091ec5d0e"
            }
          ],
          "repo": "https://github.com/agentfront/frontmcp",
          "type": "GIT"
        },
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "2.5.0"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "be3409cce6e97642696d4ee5a4e4e2712490b277"
            },
            {
              "fixed": "a8c0ff2f6fa1c072604d9c30027d8368f11a07b4"
            }
          ],
          "repo": "https://github.com/agentfront/mcp-from-openapi",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-65h7-9wrw-629c"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-918"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59973.json"
  },
  "details": "FrontMCP is a TypeScript-first framework for the Model Context Protocol (MCP). From mcp-from-openapi 2.3.0 until 2.5.0 and from frontmcp and @frontmcp/adapters 1.2.1 until 1.5.0, libs/adapters/src/openapi/openapi.adapter.ts loadOpenAPISpec() forwards untrusted OpenAPI url and spec inputs and loadOptions.refResolution to OpenAPIToolGenerator.fromURL() and OpenAPIToolGenerator.fromJSON(). The external $ref guard checks parsed hostname strings without resolving addresses, pinning validated addresses, revalidating redirect targets, or normalizing IPv4-mapped IPv6. An authenticated user who can import or configure an OpenAPI specification in a hosted or multi-user deployment can use DNS-to-loopback resolution, redirect-to-loopback behavior, or IPv4-mapped IPv6 loopback forms to cause backend-origin requests to internal services. This can expose internal administrative APIs, metadata-like services, and other private network endpoints. The practical impact is lower when only a trusted local administrator can configure OpenAPI specs, and disabling external reference protocols prevents the external $ref request. This issue is fixed in mcp-from-openapi 2.5.0 and frontmcp and @frontmcp/adapters 1.5.0.",
  "id": "CVE-2026-59973",
  "modified": "2026-09-17T03:31:01.823009041Z",
  "published": "2026-09-15T15:13:40.053Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/agentfront/frontmcp/releases/tag/v1.5.0"
    },
    {
      "type": "WEB",
      "url": "https://github.com/agentfront/mcp-from-openapi/releases/tag/v2.5.0"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59973.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/agentfront/frontmcp/security/advisories/GHSA-65h7-9wrw-629c"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-59973"
    },
    {
      "type": "FIX",
      "url": "https://github.com/agentfront/frontmcp/commit/96a78eaa5c6c4bc51cced557d83d1a03344cb03d"
    },
    {
      "type": "FIX",
      "url": "https://github.com/agentfront/frontmcp/pull/496"
    },
    {
      "type": "FIX",
      "url": "https://github.com/agentfront/mcp-from-openapi/commit/be3409cce6e97642696d4ee5a4e4e2712490b277"
    },
    {
      "type": "FIX",
      "url": "https://github.com/agentfront/mcp-from-openapi/pull/7"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "mcp-from-openapi: Bypass of OpenAPI external $ref SSRF fix in latest FrontMCP and mcp-from-openapi"
}