Ellucian Banner Self-Service before the April T2 release (2025-04-23) contains a reflected cross-site scripting vulnerability that allows unauthenticated attackers to execute arbitrary JavaScript in a victim's browser by injecting unsanitized input through the toDateFormat request parameter in the dateConverter endpoint. Attackers can craft a malicious URL targeting the unauthenticated dateConverter endpoint to steal session cookies or perform other malicious actions in the context of the victim's browser session.