n8n-MCP Workflow Telemetry URL Parameter Leak Vulnerability

A vulnerability in n8n-MCP versions prior to 2.51.3 allows the workflow telemetry sanitizer to improperly handle URL-shaped node parameters. This issue could result in the unintentional retention of sensitive information, such as customer or tenant identifiers, short secrets in query strings, and signed request parameters, which would then be sent to the project's anonymous telemetry backend. The vulnerability contradicts the data collection boundaries outlined in the project's privacy documentation.

Impact

The vulnerability could lead to the exposure of partial URL parameter fragments in the project's telemetry backend, allowing for the retrieval of sensitive information that should not have been collected.

Reproduction

The vulnerability can be reproduced by using an affected version of n8n-MCP and creating a workflow that includes URL-shaped node parameters, such as those found in HTTP request nodes. Once the workflow is executed, the telemetry data sent to the project's anonymous backend will contain unredacted fragments of the URL parameters, including any sensitive information embedded within them.

Remediation

Users can upgrade to n8n-MCP version 2.51.3 or later to address this vulnerability. For those unable to upgrade immediately, the anonymous telemetry feature can be disabled by setting the environment variables N8N_MCP_TELEMETRY_DISABLED, TELEMETRY_DISABLED, or DISABLE_TELEMETRY to true.