Open Zaak is an open-source data and services layer for Dutch case-oriented working. From 1.0.0 until 1.27.2, 1.28.2, and 1.29.0, the POST search endpoints /zaken/api/v1/zaken/_zoek and /documenten/api/v1/enkelvoudiginformatieobjecten/_zoek do not filter result querysets according to the authorizations associated with the request token. A caller with a valid zaken.lezen or documenten.lezen token can therefore retrieve case or document metadata outside the token's authorized types or confidentiality levels. Document searches require known UUIDs, and document content remains protected by separate download authorization. This issue is fixed in versions 1.27.2, 1.28.2, and 1.29.0.