{"id":"CVE-2026-59973","title":"FrontMCP is a TypeScript-first framework for the Model Context Protocol (MCP)","summary":"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 loadOpenAPISp…","severity":"high","cvss":8.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N","cwe":["CWE-918"],"vendor":"agentfront","product":"frontmcp","affected":["frontmcp < 1.5.0","mcp-from-openapi < 2.5.0","adapters < 1.5.0"],"patched":["mcp-from-openapi 2.5.0","@frontmcp/adapters 1.5.0","frontmcp 1.5.0"],"published":"2026-09-15","updated":"2026-09-16","sourceUpdated":"2026-09-16T17:17:28.750","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-59973","references":[{"url":"https://github.com/agentfront/frontmcp/commit/96a78eaa5c6c4bc51cced557d83d1a03344cb03d","label":"security-advisories@github.com"},{"url":"https://github.com/agentfront/frontmcp/pull/496","label":"security-advisories@github.com"},{"url":"https://github.com/agentfront/frontmcp/releases/tag/v1.5.0","label":"security-advisories@github.com"},{"url":"https://github.com/agentfront/frontmcp/security/advisories/GHSA-65h7-9wrw-629c","label":"security-advisories@github.com"},{"url":"https://github.com/agentfront/mcp-from-openapi/commit/be3409cce6e97642696d4ee5a4e4e2712490b277","label":"security-advisories@github.com"},{"url":"https://github.com/agentfront/mcp-from-openapi/pull/7","label":"security-advisories@github.com"},{"url":"https://github.com/agentfront/mcp-from-openapi/releases/tag/v2.5.0","label":"security-advisories@github.com"},{"url":"https://github.com/agentfront/frontmcp/security/advisories/GHSA-65h7-9wrw-629c","label":"134c704f-9b21-4f2e-91b3-4a467353bcc0"},{"url":"https://github.com/advisories/GHSA-65h7-9wrw-629c"}],"tags":["nvd","cve.org","ghsa","npm","exploit-available"],"aliases":["GHSA-65h7-9wrw-629c"],"ecosystem":"npm","exploitAvailable":true,"ssvc":{"exploitation":"poc","automatable":"no","technicalImpact":"partial","timestamp":"2026-09-16T16:06:47.172118Z"},"ingestedAt":"2026-09-12T00:03:49.069Z","epss":0.00376,"epssPercentile":0.31366,"slug":"CVE-2026-59973","body":"## Overview\n\nFrontMCP 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Package advisory (CVE-2026-59973)\n\nAffected packages:\n\n- `mcp-from-openapi >= 2.3.0, < 2.5.0`\n- `@frontmcp/adapters >= 1.2.1, < 1.5.0`\n- `frontmcp >= 1.2.1, < 1.5.0`\n\nPatched in:\n\n- `mcp-from-openapi 2.5.0`\n- `@frontmcp/adapters 1.5.0`\n- `frontmcp 1.5.0`\n\nSource: https://github.com/advisories/GHSA-65h7-9wrw-629c","depth":"midnight","depthScore":59,"depthScoreParts":{"impact":46.8,"likelihood":0.1,"exploitation":12,"ransomware":0},"changes":[{"seq":205586,"id":"CVE-2026-59973","ts":1789578064311,"field":"exploit_available","old":"false","new":"true"}]}