Is this vulnerability remotely exploitable over the internet?

Yes, if the n8n-MCP HTTP endpoint is exposed on a network reachable by the attacker and they possess a valid AUTH_TOKEN. The attack does not require direct network access to the internal services, only access to the MCP server itself.

What level of access does an attacker need?

The attacker must hold a valid AUTH_TOKEN that the server accepts and must be able to send crafted HTTP requests including the relevant multi-tenant headers. No additional OS-level or administrative access is required.

What is the safest general fix pattern?

The most robust pattern is to restrict outbound request destinations to a curated allowlist and ensure that no user-controlled data can directly specify hosts, IPs, or full URLs, especially for internal or metadata addresses. At the same time, review response handling so that internal details are not blindly reflected back to clients.

Severity:

HIGH RISK

(8.5)

Authenticated Server-Side Request Forgery (CWE-918) in n8n-MCP Multi-Tenant HTTP Interface

CVE-2026-39974

Published:

Apr 9, 2026

Status:

Analyzed

Summary

Affected Context

Exploit Preconditions

Why This Happens

Potential Impact

General Mitigation Guidance

How Teams Detect Issues Like This

Frequently Asked Questions

Source

NDV

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Vulnerability Type

Category:

Server-Side Request Forgery (SSRF)

CWE:

CWE-918

Impact:

Exposure of internal network and cloud metadata via authenticated SSRF

Severity:

HIGH RISK

(8.5)

CVSS Version:

3.1

Vulnerability Type

Category:

Server-Side Request Forgery (SSRF)

CWE:

CWE-918

Impact:

Exposure of internal network and cloud metadata via authenticated SSRF

Severity:

HIGH RISK

(8.5)

CVSS Version:

3.1

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Authenticated Server-Side Request Forgery (CWE-918) in n8n-MCP Multi-Tenant HTTP Interface

Summary

Affected Context

Exploit Preconditions

Why This Happens

Potential Impact

General Mitigation Guidance

How Teams Detect Issues Like This

Frequently Asked Questions

Source

Recent Vulnerabilities

HIGH RISK

HIGH

(8.8)

PHP Code Injection via File Upload (CWE-94) in Aero CMS Admin Post Creation

HIGH RISK

HIGH

(8.8)

Code Injection (CWE-94) via Module Parameters in Evolution CMS

Vulnerability Type

Vulnerability Type

Vulnerability Type

Catch This CVE While Code Is Being Written

Ship clean & secure code faster

Ship clean & secure code faster

Ship clean & secure code faster

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