CVE-2026-65014: n8n: Unauthenticated Endpoint Allows Cancellation of Any User's Active Test Webhook

The route DELETE /${restEndpoint}/test-webhook/:id is wired up before n8n applies its authentication middleware (CWE-306, missing authentication). A request to it needs no session or API key. If the caller supplies the ID of a workflow that currently has an active test webhook, n8n cancels that registration.

The attacker needs network access to the instance and a workflow ID. They need no account. The CVSS 4.0 vector lists no privileges, no user interaction, and a low availability impact only.

The damage is small. A developer who is waiting for a test event, such as clicking "listen for test event" in the editor, loses the registration and has to start again. The advisory states that production webhooks, persistent workflow state and stored data are not affected. The main risk is an annoyance and a signal that the REST API exposes more unauthenticated surface than expected.

Affected: n8n below 2.27.4. The entry lists no fixed 1.x release. The attacker also needs to know a workflow ID, and a test webhook must be active at that moment.

Check the version:

npm ls n8n

For Docker, check the image tag or the version in the UI.

Upgrade to n8n 2.27.4 or later. For an npm install, run npm install [email protected]. The advisory's package data also lists 2.28.0 as a patched release.

Temporary mitigations from the advisory, neither of which fully removes the risk:

• Restrict network access to the instance to fully trusted users.
• Put the instance behind a reverse proxy or firewall that requires authentication before requests reach the REST API.

Look in the reverse-proxy or access logs for DELETE requests to the test-webhook path that have no session cookie or API key, or that come from addresses outside your team. A user who reports that a test webhook stopped listening without any action on their side is a second signal. Production executions are not affected, so execution history will not show it.

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.