n8n-mcp's IPv4-mapped IPv6 addresses bypass SSRF protection in validateUrlSync(), enabling full SSRF for SDK embedders

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-42449: 0.21% estimated exploitation activity in the next 30 days; percentile 10.73 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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…

Published by the source

30 Apr 2026, 18:12 UTC

Last modified by the source

11 May 2026, 13:53 UTC

Source last checked

26 Oct 2026, 12:51 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-56c3-vfp2-5qqj

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-56c3-vfp2-5qqj

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# Patch Next advisory brief: CVE-2026-42449

Advisory: n8n-mcp's IPv4-mapped IPv6 addresses bypass SSRF protection in validateUrlSync(), enabling full SSRF for SDK embedders
IDs: CVE-2026-42449, GHSA-56c3-vfp2-5qqj
Record: https://patchnext.com/advisories/cve-2026-42449 (revision 2, source checked 26 Oct 2026, 12:51 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: n8n-mcp 2.47.14. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm n8n-mcp: affected >= 2.47.4, < 2.47.14; fixed in 2.47.14

## Suggested inspection (read-only)
- `npm ls n8n-mcp --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on n8n-mcp.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-56c3-vfp2-5qqj (OSV record GHSA-56c3-vfp2-5qqj lists affected ranges: npm n8n-mcp >=2.47.4 <2.47.14 (fixed))
- Verified: https://github.com/advisories/GHSA-56c3-vfp2-5qqj (GitHub-reviewed advisory GHSA-56c3-vfp2-5qqj lists affected ranges: npm n8n-mcp >=2.47.4 <2.47.14)

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