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CVE-2026-42449— n8n-MCP: IPv4-mapped IPv6 addresses bypass SSRF protection in validateUrlSync(), enabling full SSRF for SDK embedders

Quick assessment

Affected
czlonkowski n8n-mcp
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

n8n-MCP是Romuald Członkowski个人开发者的一个连接AI助手与自动化工作流平台的模型上下文协议服务器。 n8n-MCP 2.47.4版本至2.47.13版本存在代码问题漏洞，该漏洞源于SSRFProtection.validateUrlSync()同步URL验证器未检查IPv6地址，IPv4映射IPv6地址绕过云元数据、本地主机和私有IP范围检查，可能导致攻击者提供n8nApiUrl值时向云元数据端点、RFC1918私有网络或本地主机服务发出HTTP请求。

CVSS 8.5 · High EPSS 0.33% · P24

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 1

VendorProduct Version RangeStatus
czlonkowski n8n-mcp >= 2.47.4, < 2.47.14 affected
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I. Basic Information for CVE-2026-42449

Vulnerability Information
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Vulnerability Title
n8n-MCP: IPv4-mapped IPv6 addresses bypass SSRF protection in validateUrlSync(), enabling full SSRF for SDK embedders
Source: CVE Program / CVE List V5
Vulnerability Description
n8n-MCP is an MCP server that provides AI assistants access to n8n node documentation, properties, and operations. In versions 2.47.4 through 2.47.13, 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, 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. Projects with deployments embedding n8n-mcp as an SDK using N8NDocumentationMCPServer or N8NMCPEngine with user-supplied InstanceContext are affected. The first-party HTTP server deployment was not primarily affected — it has a second async validator (validateWebhookUrl) that catches IPv6 addresses. This issue has been fixed in version 2.47.14. If users are unable to upgrade immediately as a workaround they can validate URLs before passing to the SDK, restrict egress at the network layer, and reject user-controlled n8nApiUrl values.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
服务端请求伪造(SSRF)
Source: CVE Program / CVE List V5
Vulnerability Title
n8n-MCP 代码问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
n8n-MCP是Romuald Członkowski个人开发者的一个连接AI助手与自动化工作流平台的模型上下文协议服务器。 n8n-MCP 2.47.4版本至2.47.13版本存在代码问题漏洞，该漏洞源于SSRFProtection.validateUrlSync()同步URL验证器未检查IPv6地址，IPv4映射IPv6地址绕过云元数据、本地主机和私有IP范围检查，可能导致攻击者提供n8nApiUrl值时向云元数据端点、RFC1918私有网络或本地主机服务发出HTTP请求。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
czlonkowski n8n-mcp >= 2.47.4, < 2.47.14 -

II. Public POCs for CVE-2026-42449

# POC Description Source Link Shenlong Link
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Qwen3.6-35B-A3B · 7774 chars
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III. Intelligence Information for CVE-2026-42449

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Patches & Fixes for CVE-2026-42449 (1)

Vendor Advisories for CVE-2026-42449 (1)

IV. Related Vulnerabilities

Same product: n8n-mcp
Same vendor: czlonkowski
Same weakness: CWE-918

V. Comments for CVE-2026-42449

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