SQLAdmin: Unvalidated sortBy parameter in `ModelView` bypasses `column_sortable_list`

Summary

SQLAdmin is a flexible Admin interface for SQLAlchemy models. Prior to 0.27.1, ModelView.sort_query in sqladmin/models.py accepts the attacker-controlled sortBy list-view query parameter without enforcing the configured column_sortable_list server-side allow-list in self._sort_fields. The value is resolved with getattr and passed to relationship joins and order_by, allowing requests to sort by columns hidden from column_list and by related-model columns through dotted paths. The resulting row order forms an information-exposure oracle for unexposed values, and reversing ascending and descending order confirms their relative ordering. Pairing sortBy with searchable or filterable columns and pagination can narrow the oracle toward specific values, but exact recovery depends on the application's available fields and data. This issue is fixed in version 0.27.1.