Plane is an open-source project management tool. Prior to 1.4.0, Plane's project update endpoint authorizes the caller against the workspace slug in the request URL but loads the target project globally by UUID without binding it to that workspace. An administrator of one workspace can modify a project in another workspace when the victim project UUID is known. This violates tenant isolation and permits unauthorized cross-workspace changes to project metadata and configuration. This issue is fixed in 1.4.0.