{"id":"CVE-2026-39885","state":"PUBLISHED","title":"FrontMCP Affected by SSRF via $ref Dereferencing in Untrusted OpenAPI Specifications","description":"FrontMCP is a TypeScript-first framework for the Model Context Protocol (MCP). Prior to 2.3.0, the mcp-from-openapi library uses @apidevtools/json-schema-ref-parser to dereference $ref pointers in OpenAPI specifications without configuring any URL restrictions or custom resolvers. A malicious OpenAPI specification containing $ref values pointing to internal network addresses, cloud metadata endpoints, or local files will cause the library to fetch those resources during the initialize() call. This enables Server-Side Request Forgery (SSRF) and local file read attacks when processing untrusted OpenAPI specifications. This vulnerability is fixed in 2.3.0.","publishedAt":"2026-04-08T20:34:20.538Z","updatedAt":"2026-04-09T16:16:59.067Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["agentfront frontmcp","@frontmcp adapters","@frontmcp sdk","frontmcp mcp-from-openapi"],"affected":[{"vendor":"agentfront","product":"frontmcp","versions":[{"version":"< 1.0.4","status":"affected"}]},{"vendor":"@frontmcp","product":"adapters","versions":[{"version":"< 1.0.4","status":"affected"}]},{"vendor":"@frontmcp","product":"sdk","versions":[{"version":"< 1.0.4","status":"affected"}]},{"vendor":"frontmcp","product":"mcp-from-openapi","versions":[{"version":"<  2.3.0","status":"affected"}]}],"references":["https://github.com/agentfront/frontmcp/security/advisories/GHSA-v6ph-xcq9-qxxj","https://github.com/agentfront/frontmcp/releases/tag/v1.0.4"],"weaknesses":["CWE-918"],"ingestedAt":"2026-10-29T20:11:50.837Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/39xxx/CVE-2026-39885.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-39885","state":"PUBLISHED","datePublished":"2026-04-08T20:34:20.538Z","dateUpdated":"2026-04-09T16:16:59.067Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-04-07T20:32:03.010Z"},"containers":{"cna":{"title":"FrontMCP Affected by SSRF via $ref Dereferencing in Untrusted OpenAPI Specifications","descriptions":[{"lang":"en","value":"FrontMCP is a TypeScript-first framework for the Model Context Protocol (MCP). Prior to 2.3.0, the mcp-from-openapi library uses @apidevtools/json-schema-ref-parser to dereference $ref pointers in OpenAPI specifications without configuring any URL restrictions or custom resolvers. A malicious OpenAPI specification containing $ref values pointing to internal network addresses, cloud metadata endpoints, or local files will cause the library to fetch those resources during the initialize() call. This enables Server-Side Request Forgery (SSRF) and local file read attacks when processing untrusted OpenAPI specifications. This vulnerability is fixed in 2.3.0."}],"affected":[{"vendor":"agentfront","product":"frontmcp","versions":[{"version":"< 1.0.4","status":"affected"}]},{"vendor":"@frontmcp","product":"adapters","versions":[{"version":"< 1.0.4","status":"affected"}]},{"vendor":"@frontmcp","product":"sdk","versions":[{"version":"< 1.0.4","status":"affected"}]},{"vendor":"frontmcp","product":"mcp-from-openapi","versions":[{"version":"<  2.3.0","status":"affected"}]}],"references":[{"url":"https://github.com/agentfront/frontmcp/security/advisories/GHSA-v6ph-xcq9-qxxj","name":"https://github.com/agentfront/frontmcp/security/advisories/GHSA-v6ph-xcq9-qxxj","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/agentfront/frontmcp/releases/tag/v1.0.4","name":"https://github.com/agentfront/frontmcp/releases/tag/v1.0.4","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":7.5,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-918","lang":"en","description":"CWE-918: Server-Side Request Forgery (SSRF)","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-04-08T20:34:20.538Z"},"source":{"advisory":"GHSA-v6ph-xcq9-qxxj","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/agentfront/frontmcp/security/advisories/GHSA-v6ph-xcq9-qxxj","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-04-09T14:53:12.471902Z","id":"CVE-2026-39885","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-04-09T16:16:59.067Z"}}]}}}