GHSA-8Q49-2H5H-434X

FrontMCP: Server-Side Request Forgery (SSRF) in the OpenAPI adapter spec-change poller

// libs/adapters/src/openapi/openapi.adapter.ts, initializeGenerator()
return await OpenAPIToolGenerator.fromURL(this.options.url, {
  // ...
  followRedirects: this.options.loadOptions?.followRedirects ?? false,
  refResolution, // secure default: external $refs off, internal targets blocked
});

// libs/adapters/src/openapi/openapi-spec-poller.ts, doFetch() (vulnerable, <= 1.5.5)
const controller = new AbortController();
const timeout = setTimeout(() => controller.abort(), this.fetchTimeoutMs);
try {
  const response = await fetch(this.url, {   // <-- raw global fetch, no SSRF guard
    headers,
    signal: controller.signal,
  });
  // ...hash the body, fire onChanged...
}

import { OpenapiAdapter } from '@frontmcp/adapters';

// url is attacker-influenceable and points (directly, via DNS, or via redirect)
// at an internal target; polling re-fetches it every interval.
const adapter = OpenapiAdapter.init({
  name: 'evil',
  url: 'http://169.254.169.254/latest/meta-data/', // or http://127.0.0.1.nip.io/...
  polling: { enabled: true, intervalMs: 5000 },
});

await adapter.fetch();   // initial load IS guarded (blocked)
adapter.startPolling();  // <= 1.5.5: each poll issues an UNGUARDED GET to the internal target

A server that enables spec polling against an untrusted or attacker-influenceable
spec URL will, on every poll interval, issue a server-side GET to whatever host the
URL (or a DNS name it resolves to, or a redirect it returns) points at, including
internal-only addresses unreachable from the public internet. Consequences include:

• reading cloud-instance metadata endpoints (e.g. 169.254.169.254), credential /
  token theft;
• probing and reaching internal services and private-range hosts (internal network
  scanning);
• DNS-rebinding to swap a public host for an internal one between validation and
  connection.

The poller issues GET requests only, so the primary impact is confidentiality
(reaching and reading internal endpoints); the fetched body is content-hashed to
detect change and the subsequent tool rebuild goes back through the guarded
fromURL() path.

Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside. Typical impact: access to internal metadata services, internal APIs, or cloud credentials.

GHSA-8Q49-2H5H-434X has a CVSS score of 5.9 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.5.6); upgrading removes the vulnerable code path.

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The fix routes the poller through the same SSRF guard as the initial load, with the
same policy, so both paths share one DNS resolution + connection pinning and cannot
diverge:

• OpenApiSpecPoller.doFetch() now calls safeFetch(this.url, { headers, timeoutMs, followRedirects, ssrf }) from mcp-from-openapi instead of the global fetch().
• OpenapiAdapter.startPolling() injects the adapter's resolved policy into the
  poller: ssrf: normalizeSsrfOptions(this.resolveRefResolution()) and
  followRedirects: loadOptions?.followRedirects ?? false, identical to what
  fromURL() receives.
• SpecPollerOptions gained optional ssrf / followRedirects; standalone use of
  OpenApiSpecPoller defaults to the secure policy (internal targets blocked,
  redirects not followed).

Files changed:

• libs/adapters/src/openapi/openapi-spec-poller.ts
• libs/adapters/src/openapi/openapi-spec-poller.types.ts
• libs/adapters/src/openapi/openapi.adapter.ts

Requires mcp-from-openapi >= 2.5.0 (already a dependency at 2.5.1), which exports
safeFetch / normalizeSsrfOptions and performs the resolved-IP validation and
connection pinning.

1. What is GHSA-8Q49-2H5H-434X? GHSA-8Q49-2H5H-434X is a medium-severity server-side request forgery (SSRF) vulnerability in @frontmcp/adapters (npm), affecting versions <= 1.5.5. It is fixed in 1.5.6. Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside.
2. How severe is GHSA-8Q49-2H5H-434X? GHSA-8Q49-2H5H-434X has a CVSS score of 5.9 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of @frontmcp/adapters are affected by GHSA-8Q49-2H5H-434X? @frontmcp/adapters (npm) versions <= 1.5.5 is affected.
4. Is there a fix for GHSA-8Q49-2H5H-434X? Yes. GHSA-8Q49-2H5H-434X is fixed in 1.5.6. Upgrade to this version or later.
5. Is GHSA-8Q49-2H5H-434X exploitable, and should I be worried? Whether GHSA-8Q49-2H5H-434X is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether GHSA-8Q49-2H5H-434X is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix GHSA-8Q49-2H5H-434X? Upgrade @frontmcp/adapters to 1.5.6 or later.

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