Xibo: Missing Object-Level Authorization on /notification/export/{id} Allows Authenticated Users to Download Arbitrary Attachments

Xibo is an open source digital signage platform with a web content management system and Windows display player software. Prior to 4.4.3, missing object-level authorization on `/notification/export/{id}` allows an authenticated user to download attachments from any notification, including notifications created by administrators, by iterating over `sequential notification IDs`. Exploitation requires access to the `Notification Centre` to view past notifications, a privilege granted to non-administrators as standard. This issue is fixed in version 4.4.3.