n8n: Prototype Pollution enables confused-deputy execution via public webhooks

Impact

A prototype pollution vulnerability allowed a crafted public webhook payload to inject attacker-controlled fields into workflow data during internal object copying. These fields could be surfaced and consumed as normal values by downstream built-in nodes.

Where a workflow combines a public webhook with action nodes that consume the resulting fields, an attacker could cause the workflow to act as a confused deputy — targeting unintended records or issuing outbound requests using the workflow owner's configured credentials.

Patches

The issue has been fixed in n8n versions 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:

• Avoid exposing public (unauthenticated) webhook workflows that pass incoming data through transform nodes into action nodes with sensitive credentials or database operations.
• Limit workflow creation and editing permissions to fully trusted users only.

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