Vulnerability-Lookup

GHSA-CMRH-WVQ6-WM9R

Vulnerability from github – Published: 2026-05-08 16:59 – Updated: 2026-05-08 16:59

Summary

n8n-mcp webhook and API client paths has an authenticated SSRF

Details

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 GCP metadata.google.internal resolved 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_TOKEN to compromise).
Disable workflow management tools via DISABLED_TOOLS=n8n_trigger_webhook_workflow,n8n_create_workflow,n8n_test_workflow if the deployment does not need them.

Credit

Reported by @fg0x0.

Severity ?

7.2 (High)


                  
                    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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "n8n-mcp"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.18.7"
            },
            {
              "fixed": "2.50.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-44694"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-367",
      "CWE-918"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-08T16:59:17Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "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\u0027s 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\u0027s 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 \u2014 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).",
  "id": "GHSA-cmrh-wvq6-wm9r",
  "modified": "2026-05-08T16:59:17Z",
  "published": "2026-05-08T16:59:17Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/czlonkowski/n8n-mcp/security/advisories/GHSA-cmrh-wvq6-wm9r"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/czlonkowski/n8n-mcp"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "n8n-mcp webhook and API client paths has an authenticated SSRF"
}

CVE-2026-44694 (GCVE-0-2026-44694)

Vulnerability from cvelistv5 – Published: 2026-05-08 19:12 – Updated: 2026-05-08 19:12

Title

n8n-MCP: Authenticated SSRF in n8n-mcp webhook and API client paths

Summary

n8n-MCP is an MCP server that provides AI assistants access to n8n node documentation, properties, and operations. From version 2.18.7 to before version 2.50.2, there is an authenticated server-side request forgery vulnerability 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. This issue has been patched in version 2.50.2.

Severity ?

7.2 (High)


                        
                          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

CWE

CWE-367 - Time-of-check Time-of-use (TOCTOU) Race Condition
CWE-918 - Server-Side Request Forgery (SSRF)

Assigner

GitHub_M

References

URL

Tags

	https://github.com/czlonkowski/n8n-mcp/security/a…	x_refsource_CONFIRM
	https://github.com/czlonkowski/n8n-mcp/commit/bca…	x_refsource_MISC
	https://github.com/czlonkowski/n8n-mcp/releases/t…	x_refsource_MISC

Impacted products

	Vendor	Product	Version
	czlonkowski	n8n-mcp	Affected: >= 2.18.7, < 2.50.2

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "n8n-mcp",
          "vendor": "czlonkowski",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 2.18.7, \u003c 2.50.2"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "n8n-MCP is an MCP server that provides AI assistants access to n8n node documentation, properties, and operations. From version 2.18.7 to before version 2.50.2, there is an authenticated server-side request forgery vulnerability 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. This issue has been patched in version 2.50.2."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "HIGH",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 7.2,
            "baseSeverity": "HIGH",
            "privilegesRequired": "LOW",
            "subAvailabilityImpact": "LOW",
            "subConfidentialityImpact": "HIGH",
            "subIntegrityImpact": "LOW",
            "userInteraction": "NONE",
            "vectorString": "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",
            "version": "4.0",
            "vulnAvailabilityImpact": "LOW",
            "vulnConfidentialityImpact": "HIGH",
            "vulnIntegrityImpact": "LOW"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-367",
              "description": "CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-918",
              "description": "CWE-918: Server-Side Request Forgery (SSRF)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-08T19:12:05.326Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/czlonkowski/n8n-mcp/security/advisories/GHSA-cmrh-wvq6-wm9r",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/czlonkowski/n8n-mcp/security/advisories/GHSA-cmrh-wvq6-wm9r"
        },
        {
          "name": "https://github.com/czlonkowski/n8n-mcp/commit/bcaba839409d470abeb4a6ad9b361b553a1098eb",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/czlonkowski/n8n-mcp/commit/bcaba839409d470abeb4a6ad9b361b553a1098eb"
        },
        {
          "name": "https://github.com/czlonkowski/n8n-mcp/releases/tag/v2.50.2",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/czlonkowski/n8n-mcp/releases/tag/v2.50.2"
        }
      ],
      "source": {
        "advisory": "GHSA-cmrh-wvq6-wm9r",
        "discovery": "UNKNOWN"
      },
      "title": "n8n-MCP: Authenticated SSRF in n8n-mcp webhook and API client paths"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-44694",
    "datePublished": "2026-05-08T19:12:05.326Z",
    "dateReserved": "2026-05-07T17:07:09.316Z",
    "dateUpdated": "2026-05-08T19:12:05.326Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

GHSA-CMRH-WVQ6-WM9R

Summary

Impact

Patched Versions

Workarounds

Credit

CVE-2026-44694 (GCVE-0-2026-44694)

Tags

Sightings

Nomenclature