ILIAS before 5.1.26, 5.2.x before 5.2.15, and 5.3.x before 5.3.4, due to inconsistencies in parameter handling, is vulnerable to various instances of reflected cross-site-scripting.
Services/Form/classes/class.ilDateDurationInputGUI.php and Services/Form/classes/class.ilDateTimeInputGUI.php in ILIAS 5.1.x through 5.3.x before 5.3.4 allow XSS via an invalid date.