n8n-mcp webhook and API client paths has an authenticated SSRF
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 n8n-mcp@2.50.2.
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.
Software afectado
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| Plataforma | Paquete | Versiones vulnerables | Corregida en |
|---|---|---|---|
| Paquete de npm | n8n-mcp | >= 2.18.7, < 2.50.2 | 2.50.2 |
Referencias
- https://github.com/czlonkowski/n8n-mcp/security/advisories/GHSA-cmrh-wvq6-wm9r
- https://nvd.nist.gov/vuln/detail/CVE-2026-44694
- https://github.com/czlonkowski/n8n-mcp/commit/bcaba839409d470abeb4a6ad9b361b553a1098eb
- https://github.com/czlonkowski/n8n-mcp
- https://github.com/czlonkowski/n8n-mcp/releases/tag/v2.50.2
- Vector CVSS
CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:H/VI:L/VA:L/SC:H/SI:L/SA:L- Debilidad (CWE)
CWE-367, CWE-918- Plataforma
- npm
- Paquete
n8n-mcp- Publicada
- 08.05.2026
- Actualizado
- 11.10.2026 10:22
Fuentes y licencias
OSV / GitHub Advisory Database - GHSA-cmrh-wvq6-wm9r - CC BY 4.0
Historial de vulnerabilidades: n8n-mcp
Todas las vulnerabilidades publicadas de este paquete (Paquete de npm), de la más reciente a la más antigua. Muestra si es un fallo aislado o un paquete que hay que vigilar.
- Entradas en total
- 11
- Primera → última
- 04.2026 07.2026
- Sin corrección
- 0
- Explotada en ataques
- 0
Distribución por gravedad
- Crítica 1
- Alta 6
- Media 4
Divulgaciones por año
- 2026: 11
-
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