GHSA-4GGG-H7PH-26QR
Vulnerability from github – Published: 2026-04-08 19:53 – Updated: 2026-04-09 19:05Impact
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.
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:
1. 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.
2. 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.
3. Restrict AUTH_TOKEN distribution — ensure the bearer token is only held by fully trusted operators until you can upgrade.
Remediation
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.
Credits
Reported by the Eresus Security Research Team. @ibrahmsql
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 2.47.3"
},
"package": {
"ecosystem": "npm",
"name": "n8n-mcp"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2.47.4"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-39974"
],
"database_specific": {
"cwe_ids": [
"CWE-918"
],
"github_reviewed": true,
"github_reviewed_at": "2026-04-08T19:53:48Z",
"nvd_published_at": "2026-04-09T17:16:30Z",
"severity": "HIGH"
},
"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 \u2014 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` \u2264 `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** \u2014 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** \u2014 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** \u2014 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",
"id": "GHSA-4ggg-h7ph-26qr",
"modified": "2026-04-09T19:05:56Z",
"published": "2026-04-08T19:53:48Z",
"references": [
{
"type": "WEB",
"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": "WEB",
"url": "https://github.com/czlonkowski/n8n-mcp/commit/d9d847f230923d96e0857ccecf3a4dedcc9b0096"
},
{
"type": "PACKAGE",
"url": "https://github.com/czlonkowski/n8n-mcp"
},
{
"type": "WEB",
"url": "https://github.com/czlonkowski/n8n-mcp/releases/tag/v2.47.4"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "n8n-mcp has authenticated SSRF via instance-URL header in multi-tenant HTTP mode"
}
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.