Nextcloud Deck is a kanban style organization tool aimed at personal planning and project organization for teams integrated with Nextcloud. A database error can be generated potentially causing a DoS when performed multiple times. There are currently no known workarounds. It is recommended that the Nextcloud Server is upgraded to 1.6.5 or 1.7.3 or 1.8.2.
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-93j5-wx4c-6g88