OpenProject is open-source, web-based project management software. Prior to 17.3.2 and 17.4.0, OpenProject exposes a document update endpoint used to modify existing documents. The target document is loaded with visibility checks and then updated. During update, attacker-controlled attributes are applied to the persisted record before authorization is enforced. As a result, a user without :manage_documents in the source project can move and modify foreign project documents by setting project_id in a single PATCH request. This vulnerability is fixed in 17.3.2 and 17.4.0.