Vulnerability-Lookup

CVE-2026-45707 (GCVE-0-2026-45707)

Vulnerability from cvelistv5 – Published: 2026-05-29 13:35 – Updated: 2026-06-01 19:06

Title

n8n-MCP: Multi-tenant MCP requests fall back to process-level n8n credentials when tenant headers are absent or incomplete

Summary

n8n-MCP is an MCP server that provides AI assistants access to n8n node documentation, properties, and operations. Prior to 2.51.2, when ENABLE_MULTI_TENANT=true, the HTTP transport documents that the target n8n instance is selected per-request from x-n8n-url / x-n8n-key headers. Requests that omitted those headers — or supplied only one of them — silently fell back to the process-level N8N_API_URL / N8N_API_KEY credentials configured for the operator's own n8n instance. As a result, an authenticated MCP tenant could cause n8n management calls to execute against the operator's instance instead of its own. This affects HTTP-mode deployments of n8n-mcp that are run as a shared multi-tenant service. Single-tenant deployments (ENABLE_MULTI_TENANT unset or false) are not affected. This vulnerability is fixed in 2.51.2.

Severity

8.1 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator (v2.0.3)

CWE

CWE-284 - Improper Access Control

Assigner

GitHub_M

References

3 references

URL	Tags
https://github.com/czlonkowski/n8n-mcp/security/a…	x_refsource_CONFIRM
https://github.com/czlonkowski/n8n-mcp/commit/853…	x_refsource_MISC
https://github.com/czlonkowski/n8n-mcp/releases/t…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
czlonkowski	n8n-mcp	Affected: < 2.51.2

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-45707

Vulnerability from fkie_nvd - Published: 2026-05-29 14:16 - Updated: 2026-06-01 18:39

Severity

8.1 (High) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Summary

References

URL	Tags
security-advisories@github.com	https://github.com/czlonkowski/n8n-mcp/commit/853015d0897be7cf2d9d4726de195c938e4395ab	Patch
security-advisories@github.com	https://github.com/czlonkowski/n8n-mcp/releases/tag/v2.51.2	Product, Release Notes
security-advisories@github.com	https://github.com/czlonkowski/n8n-mcp/security/advisories/GHSA-jxx9-px88-pj69	Mitigation, Vendor Advisory

Impacted products

	Vendor	Product	Version
	n8n-mcp	n8n-mcp	*

JSON

To clipboard

{
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:n8n-mcp:n8n-mcp:*:*:*:*:*:*:*:*",
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              "versionEndExcluding": "2.51.2",
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    }
  ],
  "id": "CVE-2026-45707",
  "lastModified": "2026-06-01T18:39:40.983",
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GHSA-JXX9-PX88-PJ69

Vulnerability from github – Published: 2026-05-18 17:41 – Updated: 2026-05-18 17:41

Summary

n8n-MCP: Multi-tenant MCP requests fall back to process-level n8n credentials when tenant headers are absent or incomplete

Details

Summary

When ENABLE_MULTI_TENANT=true, the HTTP transport documents that the target n8n instance is selected per-request from x-n8n-url / x-n8n-key headers. Requests that omitted those headers — or supplied only one of them — silently fell back to the process-level N8N_API_URL / N8N_API_KEY credentials configured for the operator's own n8n instance. As a result, an authenticated MCP tenant could cause n8n management calls to execute against the operator's instance instead of its own.

This affects HTTP-mode deployments of n8n-mcp that are run as a shared multi-tenant service. Single-tenant deployments (ENABLE_MULTI_TENANT unset or false) are not affected.

Impact

An authenticated MCP tenant exploiting this path could read and write workflows, executions, data-table contents, and credential metadata on the operator's n8n instance. If the operator's n8n permits Code-node execution that reaches OS-level modules, the path could escalate to remote code execution inside the operator's n8n runtime. The process-level N8N_API_KEY is, in practice, a high-privilege key — Community Edition keys are unscoped by default, and even Enterprise scopes were configured for the operator's own needs and would carry over wholesale to a tenant who triggered the fallback.

Patches

Fixed in n8n-mcp 2.51.2. The fix:

Rejects header-less multi-tenant requests at the HTTP edge with HTTP 400 / JSON-RPC -32602 before any handler runs.
Refuses to construct an env-credential n8n API client when ENABLE_MULTI_TENANT=true.
Closes secondary leak paths in trigger handlers and in the responses of n8n_health_check, n8n_diagnostic, n8n_deploy_template, and n8n_audit_instance so the operator's URL and env-key indicator are not surfaced to tenants.

Single-tenant behavior is unchanged.

Upgrade

# NPM
npx n8n-mcp@latest

# Docker
docker pull ghcr.io/czlonkowski/n8n-mcp:latest

Workarounds

If an immediate upgrade is not possible, any one of the following reduces or eliminates exposure:

Disable multi-tenant mode. Set ENABLE_MULTI_TENANT=false (or unset it) and run a separate n8n-mcp instance per tenant with that tenant's own N8N_API_URL / N8N_API_KEY. This removes the affected code path entirely.
Reject malformed requests at a proxy. Require both x-n8n-url and x-n8n-key headers on every request and return 400 if either is missing. Neutralizes the primary header-omission path but does not address the secondary response-shape disclosures, so this is a partial mitigation only.
Reduce the blast radius of the operator API key. If your n8n instance supports API key scoping (Enterprise, or a Community Edition build that exposes scopes), provision the operator's N8N_API_KEY with the minimum scopes required for the operator's own n8n-mcp functions. This does not close the boundary break but limits what a falling-back tenant can do.

Credit

Reported by @u-ktdi.

Severity

8.1 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Show details on source website

JSON

To clipboard

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  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 2.51.1"
      },
      "package": {
        "ecosystem": "npm",
        "name": "n8n-mcp"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.51.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-45707"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-284"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-18T17:41:42Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "## Summary\n\nWhen `ENABLE_MULTI_TENANT=true`, the HTTP transport documents that the target n8n instance is selected per-request from `x-n8n-url` / `x-n8n-key` headers. Requests that omitted those headers \u2014 or supplied only one of them \u2014 silently fell back to the process-level `N8N_API_URL` / `N8N_API_KEY` credentials configured for the operator\u0027s own n8n instance. As a result, an authenticated MCP tenant could cause n8n management calls to execute against the operator\u0027s instance instead of its own.\n\nThis affects HTTP-mode deployments of `n8n-mcp` that are run as a shared multi-tenant service. Single-tenant deployments (`ENABLE_MULTI_TENANT` unset or `false`) are not affected.\n\n## Impact\n\nAn authenticated MCP tenant exploiting this path could read and write workflows, executions, data-table contents, and credential metadata on the operator\u0027s n8n instance. If the operator\u0027s n8n permits Code-node execution that reaches OS-level modules, the path could escalate to remote code execution inside the operator\u0027s n8n runtime. The process-level `N8N_API_KEY` is, in practice, a high-privilege key \u2014 Community Edition keys are unscoped by default, and even Enterprise scopes were configured for the operator\u0027s own needs and would carry over wholesale to a tenant who triggered the fallback.\n\n## Patches\n\nFixed in **n8n-mcp 2.51.2**. The fix:\n\n- Rejects header-less multi-tenant requests at the HTTP edge with HTTP 400 / JSON-RPC `-32602` before any handler runs.\n- Refuses to construct an env-credential n8n API client when `ENABLE_MULTI_TENANT=true`.\n- Closes secondary leak paths in trigger handlers and in the responses of `n8n_health_check`, `n8n_diagnostic`, `n8n_deploy_template`, and `n8n_audit_instance` so the operator\u0027s URL and env-key indicator are not surfaced to tenants.\n\nSingle-tenant behavior is unchanged.\n\n## Upgrade\n\n```bash\n# NPM\nnpx n8n-mcp@latest\n\n# Docker\ndocker pull ghcr.io/czlonkowski/n8n-mcp:latest\n```\n\n## Workarounds\n\nIf an immediate upgrade is not possible, any one of the following reduces or eliminates exposure:\n\n- **Disable multi-tenant mode.** Set `ENABLE_MULTI_TENANT=false` (or unset it) and run a separate n8n-mcp instance per tenant with that tenant\u0027s own `N8N_API_URL` / `N8N_API_KEY`. This removes the affected code path entirely.\n- **Reject malformed requests at a proxy.** Require both `x-n8n-url` and `x-n8n-key` headers on every request and return 400 if either is missing. Neutralizes the primary header-omission path but does not address the secondary response-shape disclosures, so this is a partial mitigation only.\n- **Reduce the blast radius of the operator API key.** If your n8n instance supports API key scoping (Enterprise, or a Community Edition build that exposes scopes), provision the operator\u0027s `N8N_API_KEY` with the minimum scopes required for the operator\u0027s own n8n-mcp functions. This does not close the boundary break but limits what a falling-back tenant can do.\n\n## Credit\n\nReported by [@u-ktdi](https://github.com/u-ktdi).",
  "id": "GHSA-jxx9-px88-pj69",
  "modified": "2026-05-18T17:41:42Z",
  "published": "2026-05-18T17:41:42Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/czlonkowski/n8n-mcp/security/advisories/GHSA-jxx9-px88-pj69"
    },
    {
      "type": "WEB",
      "url": "https://github.com/czlonkowski/n8n-mcp/commit/853015d0897be7cf2d9d4726de195c938e4395ab"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/czlonkowski/n8n-mcp"
    },
    {
      "type": "WEB",
      "url": "https://github.com/czlonkowski/n8n-mcp/releases/tag/v2.51.2"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "n8n-MCP: Multi-tenant MCP requests fall back to process-level n8n credentials when tenant headers are absent or incomplete"
}

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

CVE-2026-45707 (GCVE-0-2026-45707)

FKIE_CVE-2026-45707

GHSA-JXX9-PX88-PJ69

Summary

Impact

Patches

Upgrade

Workarounds

Credit

Tags

Sightings

Nomenclature