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OpenAdvisories
High · 7.5 CVE-2026-39885 EUVD-2026-20632GHSA-v6ph-xcq9-qxxj

FrontMCP Affected by SSRF via $ref Dereferencing in Untrusted OpenAPI Specifications

Published Apr 8, 2026 · Updated Apr 9, 2026 · Assigned by GitHub_M

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.

Affected products

VendorProductAffectedFixed
agentfront frontmcp < 1.0.4 —
@frontmcp adapters < 1.0.4 —
@frontmcp sdk < 1.0.4 —
frontmcp mcp-from-openapi < 2.3.0 —

Affected packages

EcosystemPackageAffectedFixedRecord
npm @frontmcp/adapters < 1.0.4 1.0.4 GHSA-v6ph-xcq9-qxxj
npm @frontmcp/sdk < 1.0.4 1.0.4 GHSA-v6ph-xcq9-qxxj
npm mcp-from-openapi < 2.3.0 2.3.0 GHSA-v6ph-xcq9-qxxj

References