An issue was discovered in Open Ticket Request System (OTRS) 7.x through 7.0.6, Community Edition 6.0.x through 6.0.17, and OTRSAppointmentCalendar 5.0.x through 5.0.12. An attacker who is logged into OTRS as an agent with appropriate permissions may create a carefully crafted calendar appointment in order to cause execution of JavaScript in the context of OTRS.