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  • AgentArmor teamTeam3d agoNeeds helpSolved

    Am I affected by OpenAPI external $ref SSRF fix bypassed in mcp-from-openapi 2.3.0 and FrontMCP 1.2.1? What should I do?

    An earlier advisory (GHSA-v6ph-xcq9-qxxj / CVE-2026-39885) published a fix that added a denylist of host names for OpenAPI external $ref links.

    Affected: mcp-from-openapi >= 2.3.0, < 2.5.0; @frontmcp/adapters >= 1.2.1, < 1.5.0; frontmcp >= 1.2.1, < 1.5.0. Fixed in: mcp-from-openapi 2.5.0, @frontmcp/adapters 1.5.0, frontmcp 1.5.0. What should you check, and what should you do about it?

    Full incident page with sources: https://agentarmorhq.com/incidents/2026/09/cve-2026-59973-mcp-from-openapi (opens external site)

    1 answer

    • Best answerAgentArmor teamTeamIncidents, compromised packages and supply chain3d ago

      Am I affected? Affected: mcp-from-openapi >= 2.3.0, < 2.5.0; @frontmcp/adapters >= 1.2.1, < 1.5.0; frontmcp >= 1.2.1, < 1.5.0. Fixed in: mcp-from-openapi 2.5.0, @frontmcp/adapters 1.5.0, frontmcp 1.5.0.

      • Check your version: run npm ls mcp-from-openapi. Versions >= 2.3.0, < 2.5.0 of mcp-from-openapi are affected.
      • Check your version: run npm ls @frontmcp/adapters. Versions >= 1.2.1, < 1.5.0 of @frontmcp/adapters are affected.
      • Check your version: run npm ls frontmcp. Versions >= 1.2.1, < 1.5.0 of frontmcp are affected.

      What to do now

      1. Upgrade to the fixed version: run npm install mcp-from-openapi@2.5.0 (first patched version 2.5.0).
      2. Upgrade to the fixed version: run npm install @frontmcp/adapters@1.5.0 (first patched version 1.5.0).
      3. Upgrade to the fixed version: run npm install frontmcp@1.5.0 (first patched version 1.5.0).
      4. Set refResolution.allowedProtocols: [] to stop the external request, but note this is not the default.
      5. Consider disabling external refs by default for untrusted OpenAPI specs and requiring explicit allowlists.

      General practice, not from the source: if the affected software could read tokens or credentials, rotate them after upgrading; pin versions and review changes before updating tools your agents run.

      Sources

      Full incident page: https://agentarmorhq.com/incidents/2026/09/cve-2026-59973-mcp-from-openapi (opens external site)

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