Nextcloud Server is a self hosted personal cloud system. A malicious user was able to send delete requests for old versions of files they only got shared with read permissions. It is recommended that the Nextcloud Server is upgraded to 26.0.12 or 27.1.7 or 28.0.3 and that the Nextcloud Enterprise Server is upgraded to 26.0.12 or 27.1.7 or 28.0.3.