n8n-mcp's IPv4-mapped IPv6 addresses bypass SSRF protection in validateUrlSync(), enabling full SSRF for SDK embedders
Impact
In the SDK embedder path (N8NDocumentationMCPServer constructor, getN8nApiClient(), and validateInstanceContext()), the synchronous URL validator in SSRFProtection.validateUrlSync() had no IPv6 checks. IPv4-mapped IPv6 addresses such as http://[::ffff:169.254.169.254] bypassed the cloud-metadata, localhost, and private-IP range checks. An attacker able to supply an n8nApiUrl value could cause the server to issue HTTP requests to cloud metadata endpoints (AWS IMDS, GCP, Azure, Alibaba, Oracle), RFC1918 private networks, or localhost services. Response bodies are returned to the caller (non-blind SSRF), and the n8nApiKey is forwarded in the x-n8n-api-key header to the attacker-controlled target.
The first-party HTTP server deployment was not primarily affected — it has a second async validator (validateWebhookUrl) that catches IPv6 addresses.
Impact category: CWE-918 (Server-Side Request Forgery).
Affected
Deployments embedding n8n-mcp as an SDK using N8NDocumentationMCPServer or N8NMCPEngine with user-supplied InstanceContext on versions v2.47.4 through v2.47.13.
Patched
v2.47.14 and later.
- npm:
npx n8n-mcp@latest(or pin to>= 2.47.14) - Docker:
docker pull ghcr.io/czlonkowski/n8n-mcp:latest
Workarounds
If developers cannot upgrade immediately:
- Validate URLs before passing to the SDK — reject any
n8nApiUrlwhose hostname is an IP literal (bracketed IPv6 or dotted IPv4) before callingN8NDocumentationMCPServer/getN8nApiClient(). Accept only URLs with DNS-resolvable hostnames. - Restrict egress at the network layer — block outbound traffic from the n8n-mcp process to RFC1918 ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16), link-local
169.254.0.0/16, and cloud metadata endpoints. Defense-in-depth against this class of issue and recommended even after upgrading. - Do not accept user-controlled
n8nApiUrlvalues — if the project's integration derives the URL from internal configuration only, this vulnerability is not reachable.
Upgrading to v2.47.14 is still strongly recommended.
Credit
Reported by @manthanghasadiya.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | n8n-mcp | >= 2.47.4, < 2.47.14 | 2.47.14 |
References
- 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
- 30.04.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-56c3-vfp2-5qqj - 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's IPv4-mapped IPv6 addresses bypass SSRF protection in validateUrlSync(), enabling full SSRF for SDK embedders this entry
Know which vulnerabilities affect your application
With the DockRay integration and software inventory enabled, DockRay checks reported component versions against known vulnerabilities and notifies you about confirmed matches. Coverage depends on the supported technology and available advisory data.