CVE-2026-39974CWE-918

n8n-MCP has an Authenticated SSRF via instance-URL header in multi-tenant HTTP mode

High · published April 9, 2026

CVSS v3.1
8.5
EPSS
0%
Percentile
36.2
In the wild
Unconfirmed
What it is

n8n-MCP is a Model Context Protocol (MCP) server that provides AI assistants with comprehensive access to n8n node documentation, properties, and operations. Prior to 2.47.4, 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. This vulnerability is fixed in 2.47.4.

The record
Technical detail
CVSS v3.1
8.5 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N
CVSS v4.0
Not supplied
EPSS
0.00431 · 36.2th percentile
Weakness
CWE-918 · Server-Side Request Forgery (SSRF)
Published
2026-04-09T16:45Z
EPSS history
Timeline
  • 09 APR 16:45Z
    n8n-MCP has an Authenticated SSRF via instance-URL header in multi-tenant HTTP mode
    cvelistv5