Nextcloud Server is a self hosted personal cloud system. When a server is configured to only allow sharing with users that are in ones own groups, after a user was removed from a group, previously shared items were not unshared. It is recommended that the Nextcloud Server is upgraded to 22.2.11 or 23.0.11 or 24.0.6 and Nextcloud Enterprise Server is upgraded to 22.2.11 or 23.0.11 or 24.0.6.
https://github.com/nextcloud/server/pull/47180
https://github.com/nextcloud/server/commit/142b6e313ffa9d3b950bcd23cb58850d3ae7cf34
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-35gc-jc6x-29cm