GHSA-cmrh-wvq6-wm9r
Fix: czlonkowski/n8n-mcp@bcaba83GHSA-cmrh-wvq6-wm9r is a security vulnerability in n8n-mcp. O3 Security confirms whether GHSA-cmrh-wvq6-wm9r is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
n8n-mcp webhook and API client paths has an authenticated SSRF
Real-World Exposure
n8n-mcpReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.
Description
Summary
Authenticated Server-Side Request Forgery affecting the webhook trigger tools, the n8n API client (N8N_API_URL), and per-request URLs supplied via the x-n8n-url header in multi-tenant HTTP mode.
Impact
A caller with access to the MCP session can drive HTTP requests from the n8n-mcp host to internal services and cloud metadata endpoints that the SSRF gate is meant to block. The response body is returned to the caller, making internal-service enumeration and credential theft immediate without any out-of-band channel.
- Multi-tenant HTTP deployments where tenants share an
AUTH_TOKEN: any tenant with valid credentials can reach the operator's cloud metadata service and exfiltrate temporary IAM / GCP service account / Azure managed-identity credentials. - Single-tenant deployments: indirect prompt injection through tool arguments reaches the same surface; an attacker who can influence the LLM's tool calls can read internal services from the n8n-mcp host.
- Stdio deployments are reachable via the same prompt-injection path.
Patched Versions
Fixed in [email protected].
Note for operators: The same SSRF gate that previously covered webhook URLs now also covers the n8n API client base URL. If N8N_API_URL points at http://localhost:5678 (n8n on the same host) or an RFC1918 address (n8n on the same private network), set WEBHOOK_SECURITY_MODE=moderate (allows localhost, still blocks RFC1918 and cloud metadata) or WEBHOOK_SECURITY_MODE=permissive (allows RFC1918 too — only safe on a trusted private network). Default strict is correct for deployments where n8n is reachable at a public hostname.
Workarounds
For deployments that cannot upgrade immediately:
- Restrict network egress from the n8n-mcp host with a firewall, reverse proxy, or cloud security group. Explicitly deny cloud metadata IPs (
169.254.169.254,169.254.170.2,100.100.100.200,192.0.0.192, and the GCPmetadata.google.internalresolved IP) and any RFC1918 networks the server does not legitimately need to reach. - Run in stdio mode instead of HTTP if the multi-tenant surface is not needed (no shared
AUTH_TOKENto compromise). - Disable workflow management tools via
DISABLED_TOOLS=n8n_trigger_webhook_workflow,n8n_create_workflow,n8n_test_workflowif the deployment does not need them.
Credit
Reported by @fg0x0.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | n8n-mcp | ≥ 2.18.7&&< 2.50.2 | 2.50.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for n8n-mcp. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update n8n-mcp to 2.50.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-cmrh-wvq6-wm9r is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-cmrh-wvq6-wm9r is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-cmrh-wvq6-wm9r. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-cmrh-wvq6-wm9r in your dependencies?
O3 detects GHSA-cmrh-wvq6-wm9r across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.