n8n-mcp has authenticated SSRF via instance-URL header in multi-tenant HTTP mode
Impact
An authenticated Server-Side Request Forgery in n8n-mcp allows a caller holding a valid AUTH_TOKEN to cause the server to issue HTTP requests to arbitrary URLs supplied through multi-tenant HTTP headers. Response bodies are reflected back through JSON-RPC, so an attacker can read the contents of any URL the server can reach — including cloud instance metadata endpoints (AWS IMDS, GCP, Azure, Alibaba, Oracle), internal network services, and any other host the server process has network access to.
The primary at-risk deployments are multi-tenant HTTP installations where more than one operator can present a valid AUTH_TOKEN, or where a token is shared with less-trusted clients. Single-tenant stdio deployments and HTTP deployments without multi-tenant headers are not affected.
Affected versions
n8n-mcp ≤ 2.47.3 (all versions up to and including 2.47.3).
Patched versions
n8n-mcp 2.47.4 and later.
Workarounds
If you cannot immediately upgrade:
- Egress filtering at the network layer — block outbound traffic from the
n8n-mcpcontainer to RFC1918 ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16), link-local169.254.0.0/16, and any other internal ranges. This defends against any future SSRF-class issue and is recommended even after upgrading. - Disable multi-tenant headers — if your deployment does not require per-request instance switching, unset
ENABLE_MULTI_TENANTand do not acceptx-n8n-url/x-n8n-keyheaders at the reverse proxy. - Restrict
AUTH_TOKENdistribution — ensure the bearer token is only held by fully trusted operators until you can upgrade.
Remediation
Upgrade to n8n-mcp 2.47.4 or later. No configuration changes are required; the fix adds validation at the URL entry points and normalizes URLs at the API client layer.
Credits
Reported by the Eresus Security Research Team. @ibrahmsql
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | n8n-mcp | < 2.47.4 | 2.47.4 |
References
- https://github.com/czlonkowski/n8n-mcp/security/advisories/GHSA-4ggg-h7ph-26qr
- https://nvd.nist.gov/vuln/detail/CVE-2026-39974
- https://github.com/czlonkowski/n8n-mcp/commit/d9d847f230923d96e0857ccecf3a4dedcc9b0096
- https://github.com/czlonkowski/n8n-mcp
- https://github.com/czlonkowski/n8n-mcp/releases/tag/v2.47.4
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N- Weakness (CWE)
CWE-918- Platform
- npm
- Package
n8n-mcp- Disclosed
- 08.04.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-4ggg-h7ph-26qr - CC BY 4.0
Vulnerability history: n8n-mcp
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 11
- First → latest
- 04.2026 07.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 1
- High 6
- Medium 4
Disclosures per year
- 2026: 11
-
n8n-mcp has authenticated SSRF via instance-URL header in multi-tenant HTTP mode this entry
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