n8n before 2.41.4 and 2.42.x before 2.42.1 contains an authorization bypass in the Agents create endpoint, which accepts a caller-supplied Agent ID, checks permissions only against the requested project, and updates an existing Agent without verifying which project owns it. An authenticated user with read-only Agent access to another project can supply an existing Agent ID to move that Agent into their own project and rewrite its name, schema and version.
Authorization Bypass Through User-Controlled Key The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.