Wekan is open source kanban built with Meteor. Prior to 9.37, Wekan DDP update allow rules in server/permissions/cards.js, server/permissions/lists.js, and server/permissions/swimlanes.js authorize against the stored source boardId and do not validate a new boardId in the update modifier. Any authenticated user with write access to their own board can call /cards/update, /lists/update, or /swimlanes/update to move cards, lists, or swimlanes into a private board they are not a member of. This issue is fixed in version 9.37.