GHSA-33q9-f52j-gc75 n8n: Unauthenticated Endpoint Allows Cancellation of Any User's Active Test Webhook

• npm n8n: < 2.27.4 → fixed in 2.27.4

Impact The `DELETE /${restEndpoint}/test-webhook/:id` route is registered before the 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. Patches Users should upgrade to the patched version once available to remediate the vulnerability. Workarounds If upgrading is not immediately possible, administrators should consider the following temporary mitigations: • Restrict network access to the n8n instance to fully trusted users only. • Place the n8n instance behind a reverse proxy or firewall that requires authentication before reaching the REST API. These workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.