CVE-2026-42226: n8n's Credential Authorization Bypass in dynamic-node-parameters Allows Foreign API Key Replay

The dynamic-node-parameters endpoints did not verify whether the authenticated caller was authorized to use a supplied credential reference. An authenticated user with access to a shared workflow could supply a foreign credential ID in the request body, causing the backend to decrypt and use that credential in a helper execution path where the caller also controls the destination URL. This allowed the caller to force the backend to authenticate against attacker-controlled infrastructure using a credential belonging to another user, effectively exfiltrating a reusable API key.

The issue is not limited to any single node type; any node that resolves credentials dynamically through these endpoints may be affected.