n8n before 1.123.83, 2.x before 2.41.4, and 2.42.x before 2.42.1 contains an authentication bypass because dynamic-path webhook resolution matched requests on the path alone, ignoring the server-generated identifier that is the URL's only unguessable component. Unauthenticated attackers can omit this identifier in requests to webhook, form, or MCP routes to execute workflows in unrelated projects under those projects' credentials.
Authentication Bypass Using an Alternate Path or Channel The product requires authentication, but the product has an alternate path or channel that does not require authentication.