GHSA-f3rg-xqjj-cj9w

## Summary

In affected versions of n8n-mcp, the workflow telemetry sanitizer could retain partial fragments of URL-shaped node parameters before sending workflow data to the project's anonymous telemetry backend. Values placed in HTTP-Request-style node parameters — such as customer or tenant identifiers, short secrets embedded in query strings, and signed request parameters — could therefore appear in stored telemetry, contrary to the collection boundary documented in `PRIVACY.md`.

## Impact

Operators with access to the project's telemetry backend could read partial fragments of workflow URL parameters that should not have been collected. The bug was scoped to URL-shaped fields in workflow *definitions*; credentials, OAuth tokens, and workflow *execution* data are not affected — credentials are removed by a separate code path, and long secrets and known-provider tokens are matched by dedicated patterns.

## Patches

Fixed in **n8n-mcp `2.51.3`**. Upgrading is the recommended remediation.

## Workarounds

For users who cannot upgrade immediately, disable anonymous telemetry by setting any of these environment variables to `true`:

- `N8N_MCP_TELEMETRY_DISABLED` - `TELEMETRY_DISABLED` - `DISABLE_TELEMETRY`

## Credit

Reported by @u-ktdi.