Xibo is an open source digital signage platform with a web content management system and Windows display player software. A stored Cross-Site Scripting (XSS) vulnerability in versions prior to 4.4.1 allows an authenticated user with notification creation permissions to inject arbitrary JavaScript into the notification body. When the notification is set as an "interrupt," the payload executes automatically in the browser of any targeted user upon login, requiring zero user interaction. Exploitation of the vulnerability is possible on behalf of an authorized user who has both of the following privileges, which are not granted to non-admins as standard: Access to the Notification Centre to view past notifications, and include "Add Notification" button to allow for the creation of new notifications. Users should upgrade to version 4.4.1 which fixes this issue. Upgrading to a fixed version is necessary to remediate. Users unable to upgrade should revoke such privileges from users they do not trust.