GHSA-gwj8-fp64-q94q: 
JavaScript vulnerability analysis and mitigation

Impact

In affected versions, the synchronous URL check used for instance URLs accepted some alternative spellings of private, loopback and cloud-metadata IPv4 addresses. Requests to these addresses were still refused by the DNS-resolving validation and the DNS-pinned HTTP agents, so the impact is limited to the pre-check layer (defence in depth).

Patches

Fixed in 2.101.1.

Workarounds

Restrict network egress from the n8n-mcp host, or use stdio mode.

Credit

Found in an internal security review.