Duplicate Advisory: Unauthenticated Endpoint Allows Cancellation of Any User's Active Test Webhook
This advisory has been withdrawn because it is a duplicate of GHSA-33q9-f52j-gc75. This link is maintained to preserve external references.
n8n before 2.28.0 (and before 2.27.4 on the 2.27.x branch) registers the DELETE /${restEndpoint}/test-webhook/:id endpoint before authentication middleware is applied, allowing any unauthenticated network caller who knows a workflow ID to cancel that workflow's active test webhook registration. The impact is limited to disrupting in-progress test sessions; production webhooks, persistent workflow state, and stored data are not affected.