In Progress® Kendo® UI for jQuery prior to 2026.4.1111 the TabStrip, PanelBar, and Menu widgets support mapping a dataSource field to `spriteCssClass`. If an attacker can control the mapped data, they can break out of the attribute and inject markup, including event-handler attributes. The resulting JavaScript executes in the application's origin when a victim loads a page that renders the affected widget, allowing access to data and actions available in the victim's authenticated session.

In Progress® Kendo® UI for jQuery prior to 2026.4.1111 the TabStrip, PanelBar, and Menu widgets support mapping a dataSource field to `spriteCssClass`. If an attacker can control the mapped data, they can break out of the attribute and inject markup, including event-handler attributes. The resulting JavaScript executes in the application's origin when a victim loads a page that renders the affected widget, allowing access to data and actions available in the victim's authenticated session.