Answer in brief
CVE-2026-59973 records a High severity (CVSS 8.5) vulnerability in mcp-from-openapi: Bypass of OpenAPI external $ref SSRF fix in latest FrontMCP and mcp-from-openapi. The current sources do not mark it as known exploited. The current feed maps @frontmcp/adapters (generic), agentfront/frontmcp (generic), agentfront/mcp-from-openapi (generic), frontmcp (npm) and additional mapped packages. Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 8.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps @frontmcp/adapters (generic), agentfront/frontmcp (generic), agentfront/mcp-from-openapi (generic), frontmcp (npm) and additional mapped packages. Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| @frontmcp/adaptersgeneric | < 1.5.0 | Not reported |
| agentfront/frontmcpgeneric | < 1.5.0 | Not reported |
| agentfront/mcp-from-openapigeneric | < 2.5.0 | Not reported |
| frontmcpnpm | >=1.2.1,<1.5.0 | 1.5.0 |
| frontmcpnpm | >=1.2.1 <1.5.0 | 1.5.0 |
| @frontmcp/adaptersnpm | >=1.2.1,<1.5.0 | 1.5.0 |
| @frontmcp/adaptersnpm | >=1.2.1 <1.5.0 | 1.5.0 |
| mcp-from-openapinpm | >=2.3.0,<2.5.0 | 2.5.0 |
| mcp-from-openapinpm | >=2.3.0 <2.5.0 | 2.5.0 |
Published upstream
Sep 15, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Sep 15, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Sep 11, 2026
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.
Quoted source text, attributed separately from HOL analysis.