Summary
Affected versions
n8n-mcp ≤ 2.47.3 (all versions up to and including 2.47.3).
Patched versions
n8n-mcp 2.47.4 and later.
Workarounds
If you cannot immediately upgrade:
- Egress filtering at the network layer, block outbound traffic from the
n8n-mcpcontainer to RFC1918 ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16), link-local169.254.0.0/16, and any other internal ranges. This defends against any future SSRF-class issue and is recommended even after upgrading. - Disable multi-tenant headers, if your deployment does not require per-request instance switching, unset
ENABLE_MULTI_TENANTand do not acceptx-n8n-url/x-n8n-keyheaders at the reverse proxy. - Restrict
AUTH_TOKENdistribution, ensure the bearer token is only held by fully trusted operators until you can upgrade.
Credits
Reported by the Eresus Security Research Team. @ibrahmsql
Impact
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.
Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside. Typical impact: access to internal metadata services, internal APIs, or cloud credentials.
CVE-2026-39974 has a CVSS score of 8.5 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.47.4); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
Upgrade to n8n-mcp 2.47.4 or later. No configuration changes are required; the fix adds validation at the URL entry points and normalizes URLs at the API client layer.
Frequently Asked Questions
- What is CVE-2026-39974? CVE-2026-39974 is a high-severity server-side request forgery (SSRF) vulnerability in n8n-mcp (npm), affecting versions <= 2.47.3. It is fixed in 2.47.4. Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside.
- How severe is CVE-2026-39974? CVE-2026-39974 has a CVSS score of 8.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of n8n-mcp are affected by CVE-2026-39974? n8n-mcp (npm) versions <= 2.47.3 is affected.
- Is there a fix for CVE-2026-39974? Yes. CVE-2026-39974 is fixed in 2.47.4. Upgrade to this version or later.
- Is CVE-2026-39974 exploitable, and should I be worried? Whether CVE-2026-39974 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-39974 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-39974? Upgrade
n8n-mcpto 2.47.4 or later.