CVE-2026-59973

{"id": "CVE-2026-59973", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-59973", "role": "CISA Coordinator", "options": [{"exploitation": "poc"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-09-16T16:06:47.172118Z"}}], "cvssMetricV31": [{"type": "Secondary", "source": "security-advisories@github.com", "cvssData": {"scope": "CHANGED", "version": "3.1", "baseScore": 8.5, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N", "integrityImpact": "LOW", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "LOW", "confidentialityImpact": "HIGH"}, "impactScore": 4.7, "exploitabilityScore": 3.1}]}, "affected": [{"source": "security-advisories@github.com", "affectedData": [{"vendor": "agentfront", "product": "frontmcp", "versions": [{"status": "affected", "version": "< 1.5.0"}]}, {"vendor": "agentfront", "product": "mcp-from-openapi", "versions": [{"status": "affected", "version": "< 2.5.0"}]}, {"vendor": "@frontmcp", "product": "adapters", "versions": [{"status": "affected", "version": "< 1.5.0"}]}]}], "published": "2026-09-15T16:17:18.327", "references": [{"url": "https://github.com/agentfront/frontmcp/commit/96a78eaa5c6c4bc51cced557d83d1a03344cb03d", "source": "security-advisories@github.com"}, {"url": "https://github.com/agentfront/frontmcp/pull/496", "source": "security-advisories@github.com"}, {"url": "https://github.com/agentfront/frontmcp/releases/tag/v1.5.0", "source": "security-advisories@github.com"}, {"url": "https://github.com/agentfront/frontmcp/security/advisories/GHSA-65h7-9wrw-629c", "source": "security-advisories@github.com"}, {"url": "https://github.com/agentfront/mcp-from-openapi/commit/be3409cce6e97642696d4ee5a4e4e2712490b277", "source": "security-advisories@github.com"}, {"url": "https://github.com/agentfront/mcp-from-openapi/pull/7", "source": "security-advisories@github.com"}, {"url": "https://github.com/agentfront/mcp-from-openapi/releases/tag/v2.5.0", "source": "security-advisories@github.com"}, {"url": "https://github.com/agentfront/frontmcp/security/advisories/GHSA-65h7-9wrw-629c", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"}], "vulnStatus": "Received", "weaknesses": [{"type": "Secondary", "source": "security-advisories@github.com", "description": [{"lang": "en", "value": "CWE-918"}]}], "descriptions": [{"lang": "en", "value": "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."}], "lastModified": "2026-09-16T17:17:28.750", "sourceIdentifier": "security-advisories@github.com"}