n8n before 2.41.4 and 2.42.1 Cross-Project Agent Ownership Transfer via Agents Create Endpoint

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.