Plane is an open-source project management tool. Prior to 1.4.0, multiple issue-listing endpoints, including unauthenticated public deploy boards handled by IssueListSpaceEndpoint in apps/api/plane/space/views/issue.py, pass the user-controlled order_by parameter through order_issue_queryset in apps/api/plane/utils/order_queryset.py to Django's order_by without allowlist validation. An attacker can use double-underscore relationship traversal to reference arbitrary related model fields, revealing database schema details through errors and potentially disclosing field values through differential ordering. This issue is fixed in version 1.4.0.