CVE-2026-44694: N8n mcp N8n-mcp Webhook And API Client Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-cmrh-wvq6-wm9r",
  "modified" : "2026-05-13T13:35:05Z",
  "published" : "2026-05-08T16:59:17Z",
  "aliases" : [ "CVE-2026-44694" ],
  "summary" : "n8n-mcp webhook and API client paths has an authenticated SSRF",
  "details" : "### Summary\n\nAuthenticated 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.\n\n### Impact\n\nA 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.\n\n- **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.\n- **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.\n- **Stdio deployments** are reachable via the same prompt-injection path.\n\n### Patched Versions\n\nFixed in `n8n-mcp@2.50.2`.\n\n**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.\n\n### Workarounds\n\nFor deployments that cannot upgrade immediately:\n\n1. **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 GCP `metadata.google.internal` resolved IP) and any RFC1918 networks the server does not legitimately need to reach.\n2. **Run in stdio mode** instead of HTTP if the multi-tenant surface is not needed (no shared `AUTH_TOKEN` to compromise).\n3. **Disable workflow management tools** via `DISABLED_TOOLS=n8n_trigger_webhook_workflow,n8n_create_workflow,n8n_test_workflow` if the deployment does not need them.\n\n### Credit\n\nReported by [@fg0x0](https://github.com/fg0x0).",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "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"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "n8n-mcp"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.18.7"
      }, {
        "fixed" : "2.50.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/czlonkowski/n8n-mcp/security/advisories/GHSA-cmrh-wvq6-wm9r"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-44694"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/czlonkowski/n8n-mcp/commit/bcaba839409d470abeb4a6ad9b361b553a1098eb"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/czlonkowski/n8n-mcp"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/czlonkowski/n8n-mcp/releases/tag/v2.50.2"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-367", "CWE-918" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-08T16:59:17Z",
    "nvd_published_at" : "2026-05-08T20:16:31Z"
  }
}