CVE-2026-59973
- Source
- https://cve.org/CVERecord?id=CVE-2026-59973
- Import Source
- https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-59973.json
- JSON Data
- https://api.osv.dev/v1/vulns/CVE-2026-59973
- Aliases
- Published
- 2026-09-15T15:13:40Z
- Modified
- 2026-10-28T02:31:07Z
- Severity
-
- 8.5 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N CVSS Calculator
- Summary
- mcp-from-openapi: Bypass of OpenAPI external $ref SSRF fix in latest FrontMCP and mcp-from-openapi
- 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.
- 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" }- References
-
- https://github.com/agentfront/frontmcp/releases/tag/v1.5.0
- https://github.com/agentfront/mcp-from-openapi/releases/tag/v2.5.0
- https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59973.json
- https://github.com/agentfront/frontmcp/security/advisories/GHSA-65h7-9wrw-629c
- https://nvd.nist.gov/vuln/detail/CVE-2026-59973
- https://github.com/agentfront/frontmcp/commit/96a78eaa5c6c4bc51cced557d83d1a03344cb03d
- https://github.com/agentfront/frontmcp/pull/496
- https://github.com/agentfront/mcp-from-openapi/commit/be3409cce6e97642696d4ee5a4e4e2712490b277
- https://github.com/agentfront/mcp-from-openapi/pull/7
Affected packages
Git / github.com/agentfront/frontmcp
Affected ranges
- Type
- GIT
- Repo
- https://github.com/agentfront/frontmcp
- Events
-
Introduced0 Unknown introduced commit / All previous commits are affectedFixedFixed
- Database specific
-
Show details
{ "extracted_events": [ { "range": [ { "introduced": "0" }, { "fixed": "1.5.0" } ], "source": "AFFECTED_FIELD", "strategy": "StringRangeExpression" }, { "range": [ { "fixed": "96a78eaa5c6c4bc51cced557d83d1a03344cb03d" } ], "source": "REFERENCES_COMMIT" }, { "original_tag": "v1.5.0", "range": [ { "fixed": "c1740dc4fd6a10e42f771b2c7715d2e091ec5d0e" } ], "source": "REFERENCES_TAG" } ] }
- Type
- GIT
- Repo
- https://github.com/agentfront/mcp-from-openapi
- Events
-
Introduced0 Unknown introduced commit / All previous commits are affectedFixedFixed
- Database specific
-
Show details
{ "extracted_events": [ { "range": [ { "introduced": "0" }, { "fixed": "2.5.0" } ], "source": "AFFECTED_FIELD", "strategy": "StringRangeExpression" }, { "range": [ { "fixed": "be3409cce6e97642696d4ee5a4e4e2712490b277" } ], "source": "REFERENCES_COMMIT" }, { "original_tag": "v2.5.0", "range": [ { "fixed": "a8c0ff2f6fa1c072604d9c30027d8368f11a07b4" } ], "source": "REFERENCES_TAG" } ] }