XWiki Platform is a generic wiki platform offering runtime services for applications built on top of it. It's possible for any user knowing the ID of a notification filter preference of another user, to enable/disable it or even delete it. The impact is that the target user might start loosing notifications on some pages because of this. This vulnerability is present in XWiki since 13.2-rc-1. This vulnerability has been patched in XWiki 14.10.21, 15.5.5, 15.10.1, 16.0-rc-1. The patch consists in checking properly the rights of the user before performing any action on the filters. Users are advised to upgrade. It's possible to fix manually the vulnerability by editing the document `XWiki.Notifications.Code.NotificationPreferenceService` to apply the changes performed in commit e8acc9d8e6af7dfbfe70716ded431642ae4a6dd4.