BREW-n8n-mcp-CVE-2026-42449 — n8n-mcp's IPv4-mapped IPv6 addresses bypass SSRF protection in validateUrlSync(), enabling full SSRF for SDK embedders

Affected: Homebrew: n8n-mcp

### Impact

In the SDK embedder path (`N8NDocumentationMCPServer` constructor, `getN8nApiClient()`, and `validateInstanceContext()`), the synchronous URL validator in `SSRFProtection.validateUrlSync()` had no IPv6 checks. IPv4-mapped IPv6 addresses such as `http://[::ffff:169.254.169.254]` bypassed the cloud-metadata, localhost, and private-IP range checks. An attacker able to supply an `n8nApiUrl` value could cause the server to issue HTTP requests to cloud metadata endpoints (AWS IMDS, GCP, Azure, Alibaba, Oracle), RFC1918 private networks, or localhost services. Response bodies are returned to the caller (non-blind SSRF), and the `n8nApiKey` is forwarded in the `x-n8n-api-key` header to the attacker-controlled target.

The first-party HTTP server deployment was not primarily affected — it has a second async validator (`validateWebhookUrl`) that catches IPv6 addresses.

Impact category: **CWE-918** (Server-Side Request Forgery).

### Affected

Deployments embedding n8n-mcp as an SDK using `N8NDocumentationMCPServer` or `N8NMCPEngine` with user-supplied `InstanceContext` on versions **v2.47.4 through v2.47.13**.

### Patched

**v2.47.14** and later.

- npm: `npx n8n-mcp@latest` (or pin to `>= 2.47.14`) - Docker: `docker pull ghcr.io/czlonkowski/n8n-mcp:latest`

### Workarounds

If developers cannot upgrade immediately:

- **Validate URLs before passing to the SDK** — reject any `n8nApiUrl` whose hostname is an IP literal (bracketed IPv6 or dotted IPv4) before calling `N8NDo…

CVE-2026-42449 — n8n-MCP: IPv4-mapped IPv6 addresses bypass SSRF protection in validateUrlSync(), enabling full SSRF for SDK embedders

Affected: czlonkowski n8n-mcp

n8n-MCP is an MCP server that provides AI assistants access to n8n node documentation, properties, and operations. In versions 2.47.4 through 2.47.13, the SDK embedder path (N8NDocumentationMCPServer constructor, getN8nApiClient(), and validateInstanceContext()), the synchronous URL validator in SSRFProtection.validateUrlSync() had no IPv6 checks. IPv4-mapped IPv6 addresses such as http://[::ffff:169.254.169.254] bypassed the cloud-metadata, localhost, and private-IP range checks. An attacker able to supply an n8nApiUrl value could cause the server to issue HTTP requests to cloud metadata endpoints, RFC1918 private networks, or localhost services. Response bodies are returned to the caller (non-blind SSRF), and the n8nApiKey is forwarded in the x-n8n-api-key header to the attacker-controlled target. Projects with deployments embedding n8n-mcp as an SDK using N8NDocumentationMCPServer or N8NMCPEngine with user-supplied InstanceContext are affected. The first-party HTTP server deployment was not primarily affected — it has a second async validator (validateWebhookUrl) that catches IPv6 addresses. This issue has been fixed in version 2.47.14. If users are unable to upgrade immediately as a workaround they can validate URLs before passing to the SDK, restrict egress at the network layer, and reject user-controlled n8nApiUrl values.

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BREW-n8n-mcp-CVE-2026-42449 — n8n-mcp's IPv4-mapped IPv6 addresses bypass SSRF protection in validateUrlSync(), enabling full SSRF for SDK embedders

CVE-2026-42449 — n8n-MCP: IPv4-mapped IPv6 addresses bypass SSRF protection in validateUrlSync(), enabling full SSRF for SDK embedders