Package Instance

n8n-MCP Logs Sensitive Request Data on Unauthorized /mcp Requests
### Impact

When `n8n-mcp` runs in HTTP transport mode, incoming requests to the `POST /mcp` endpoint had their request metadata written to server logs regardless of the authentication outcome. In deployments where logs are collected, forwarded to external systems, or viewable outside the request trust boundary (shared log storage, SIEM pipelines, support/ops access), this can result in disclosure of:

- bearer tokens from the `Authorization` header
- per-tenant API keys from the `x-n8n-key` header in multi-tenant setups
- JSON-RPC request payloads sent to the MCP endpoint

Access control itself was not bypassed — unauthenticated requests were correctly rejected with `401 Unauthorized` — but sensitive values from those rejected requests could still be persisted in logs.

Impact category: **CWE-532** (Insertion of Sensitive Information into Log File).

### Affected

Deployments running n8n-mcp **v2.47.10 or earlier** in HTTP transport mode (`MCP_MODE=http`). The stdio transport is not affected.

### Patched

**v2.47.11** and later.

- npm: `npx n8n-mcp@latest` (or pin to `>= 2.47.11`)
- Docker: `docker pull ghcr.io/czlonkowski/n8n-mcp:latest`

### Workarounds

If users cannot upgrade immediately:

- Restrict network access to the HTTP port (firewall, reverse proxy, or VPN) so only trusted clients can reach the endpoint.
- Switch to stdio transport (`MCP_MODE=stdio`, the default for CLI invocation), which has no HTTP surface.

### Credit

n8n-MCP thanks [@S4nso](https://github.com/S4nso) (Organization / Jormungandr) for reporting this issue.

n8n-mcp has authenticated SSRF via instance-URL header in multi-tenant HTTP mode
## 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.

## 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

n8n-MCP: Sensitive MCP tool-call arguments logged on authenticated requests in HTTP mode
### Impact

When `n8n-mcp` runs in HTTP transport mode, authenticated MCP `tools/call` requests had their full arguments and JSON-RPC params written to server logs by the request dispatcher and several sibling code paths before any redaction. When a tool call carries credential material — most notably `n8n_manage_credentials.data` — the raw values can be persisted in logs.

In deployments where logs are collected, forwarded to external systems, or viewable outside the request trust boundary (shared log storage, SIEM pipelines, support/ops access), this can result in disclosure of:

- bearer tokens and OAuth credentials sent through `n8n_manage_credentials`
- per-tenant API keys and webhook auth headers embedded in tool arguments
- arbitrary secret-bearing payloads passed to any MCP tool

The issue requires authentication (`AUTH_TOKEN` accepted by the server), so unauthenticated callers cannot trigger it; the runtime exposure is also reduced by an existing console-silencing layer in HTTP mode, but that layer is fragile and the values are still constructed and passed into the logger. The fix removes the leak at the source.

Impact category: **CWE-532** (Insertion of Sensitive Information into Log File). CVSS 3.1 score: **4.3 Medium** (`AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N`).

### Affected

Deployments running n8n-mcp **v2.47.12 or earlier** in HTTP transport mode (`MCP_MODE=http`). The stdio transport short-circuits the relevant log calls and is not affected in practice.

### Patched

**v2.47.13** and later.

- npm: `npx n8n-mcp@latest` (or pin to `>= 2.47.13`)
- Docker: `docker pull ghcr.io/czlonkowski/n8n-mcp:latest`

The patch routes tool-call arguments through a metadata-only summarizer (`summarizeToolCallArgs`) that records type, top-level key names, and approximate size — never values. The same pattern was adopted earlier for HTTP request bodies in GHSA-pfm2-2mhg-8wpx.

### Workarounds

If developers cannot upgrade immediately:

- Restrict access to the HTTP port (firewall, reverse proxy, or VPN) so only trusted clients can authenticate.
- Restrict access to server logs (no shared SIEM ingestion, no support read-only access) until the upgrade lands.
- Switch to stdio transport (`MCP_MODE=stdio`, the default for CLI invocation), which has no HTTP surface and short-circuits the affected log calls.

### Credit

n8n-MCP thanks [@Mirr2](https://github.com/Mirr2) (Organization / Jormungandr) for reporting this issue.

n8n-mcp affected by path traversal, redirect-following SSRF, and telemetry payload exposure
## Impact

`n8n-mcp` versions before 2.50.1 contained three independently-reported issues affecting deployments that run the n8n API integration:

1. **Caller-supplied identifiers were not validated before being used as URL path segments** by the n8n API client. An authenticated MCP caller passing a crafted workflow id could cause outbound requests carrying the configured n8n API key to land on other same-origin endpoints, bypassing handler-level access controls (including `DISABLED_TOOLS`).

2. **Validated webhook, form, and chat trigger URLs followed redirects.** A URL that passed initial validation could redirect the outbound request to a host that would otherwise have been rejected, with the response body returned to the caller. Reachable as non-blind SSRF over authenticated MCP calls.

3. **Mutation telemetry stored unredacted operation payloads.** On instances running with the default opt-in telemetry, partial-update operation diffs were uploaded without redaction. Operation values can carry the same node-parameter values the workflow contains, including bearer tokens, API keys, and webhook secrets.

## Severity

CVSS 8.3 (HIGH). Exploitation requires an authenticated MCP caller and an n8n API integration configured with an n8n API key.

## Patched versions

Upgrade to `n8n-mcp >= 2.50.1`.

## Workarounds

- For issues (1) and (2): restrict network access to the HTTP transport (firewall, reverse-proxy ACL, or VPN) so only trusted callers can reach the MCP HTTP port; or switch to stdio mode, which exposes no HTTP surface for these issues.
- For issue (3): set `N8N_MCP_TELEMETRY_DISABLED=true` in the environment before starting the server, or run `npx n8n-mcp telemetry disable` once.

## Credit

Reported by @cybercraftsolutionsllc.

n8n-mcp has unauthenticated session termination and information disclosure in HTTP transport
### Summary

Several HTTP transport endpoints in n8n-mcp lacked proper authentication, and the health check endpoint exposed sensitive operational metadata without credentials.

### Impact

An unauthenticated attacker with network access to the n8n-mcp HTTP server could disrupt active MCP sessions and gather information useful for further attacks.

### Patches

Fixed in **v2.47.6**. All MCP session endpoints now require Bearer authentication. The health check endpoint has been reduced to a minimal liveness response.

### Workarounds

If you cannot upgrade immediately:

- **Restrict network access** to the HTTP server using firewall rules, reverse proxy IP allowlists, or a VPN so that only trusted clients can reach it.
- **Use stdio mode** (`MCP_MODE=stdio`) instead of HTTP mode. The stdio transport does not expose any HTTP endpoints and is unaffected by this vulnerability.

Upgrading to v2.47.6 is still strongly recommended.

### Credit

Reported by @yotampe-pluto.