Nextcloud Tables allows you to create your own tables with individual columns. Prior to 0.8.7 and 0.9.4, authenticated users were able to view meta data of columns in other tables of the Tables app by modifying the numeric ID in a request. This vulnerability is fixed in 0.8.7 and 0.9.4.
https://hackerone.com/reports/3138721
https://github.com/nextcloud/tables/pull/1891
https://github.com/nextcloud/tables/commit/e975f5bfedb6922f04cdd236cde4e26067fe064e
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-p53h-6294-crjw