{"id":"CVE-2026-39974","aliases":["GHSA-4ggg-h7ph-26qr"],"url":"https://o3.security/vulnerability/CVE-2026-39974","summary":"n8n-MCP has an Authenticated SSRF via instance-URL header in multi-tenant HTTP mode","details":"## Impact\nAn 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.\n\nThe 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.\n\n## Affected versions\n`n8n-mcp` ≤ `2.47.3` (all versions up to and including 2.47.3).\n\n## Patched versions\n`n8n-mcp` `2.47.4` and later.\n\n## Workarounds\nIf you cannot immediately upgrade:\n1. **Egress filtering at the network layer** — block outbound traffic from the `n8n-mcp` container to RFC1918 ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16), link-local `169.254.0.0/16`, and any other internal ranges. This defends against any future SSRF-class issue and is recommended even after upgrading.\n2. **Disable multi-tenant headers** — if your deployment does not require per-request instance switching, unset `ENABLE_MULTI_TENANT` and do not accept `x-n8n-url` / `x-n8n-key` headers at the reverse proxy.\n3. **Restrict `AUTH_TOKEN` distribution** — ensure the bearer token is only held by fully trusted operators until you can upgrade.\n\n## Remediation\nUpgrade 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.\n\n## Credits\nReported by the Eresus Security Research Team. @ibrahmsql","published":"2026-04-09T16:45:20.490Z","modified":"2026-08-12T03:51:38.293164768Z","cvss":{"score":8.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N"},"epss":{"score":0.00316,"percentile":0.24334,"asOf":"2026-08-18"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"n8n-mcp","fixedVersion":"2.47.4"}],"fix":{"url":"https://github.com/czlonkowski/n8n-mcp/commit/d9d847f230923d96e0857ccecf3a4dedcc9b0096","label":"czlonkowski/n8n-mcp@d9d847f"},"references":[{"type":"WEB","url":"https://github.com/czlonkowski/n8n-mcp/releases/tag/v2.47.4"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/39xxx/CVE-2026-39974.json"},{"type":"ADVISORY","url":"https://github.com/czlonkowski/n8n-mcp/security/advisories/GHSA-4ggg-h7ph-26qr"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-39974"},{"type":"FIX","url":"https://github.com/czlonkowski/n8n-mcp/commit/d9d847f230923d96e0857ccecf3a4dedcc9b0096"},{"type":"PACKAGE","url":"https://github.com/czlonkowski/n8n-mcp"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:38.293164768Z"}}