---
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: 0.00393
epssPercentile: 0.30722
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2026-59973)

Affected packages:

- `mcp-from-openapi >= 2.3.0, < 2.5.0`
- `@frontmcp/adapters >= 1.2.1, < 1.5.0`
- `frontmcp >= 1.2.1, < 1.5.0`

Patched in:

- `mcp-from-openapi 2.5.0`
- `@frontmcp/adapters 1.5.0`
- `frontmcp 1.5.0`

Source: https://github.com/advisories/GHSA-65h7-9wrw-629c