n8n: Same-Origin XSS in Respond to Webhook Node

Impact

An authenticated user with workflow edit access could configure a Respond to Webhook node to serve binary content with an attacker-controlled Content-Type. The binary response path bypassed the central Content-Security-Policy sandbox header, allowing a public webhook to execute JavaScript in the n8n origin when visited by an authenticated user, with access to that user's session.

Patches

The issue has been fixed in n8n versions 1.123.55, 2.25.7, and 2.26.2. Users should upgrade to one of these versions or later to remediate the vulnerability.

Workarounds

If upgrading is not immediately possible, administrators should consider the following temporary mitigations:

• Limit workflow creation and editing permissions to fully trusted users only.
• Disable the Respond to Webhook node by adding n8n-nodes-base.respondToWebhook to the NODES_EXCLUDE environment variable.

These workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.