The Calendar module in Liferay Portal 7.2.0 through 7.4.2, and older unsupported versions, and Liferay DXP 7.3 before service pack 3, 7.2 before fix pack 15, and older unsupported versions does not escape user supplied data in the default notification email template, which allows remote authenticated users to inject arbitrary web script or HTML via the title of a calendar event or the user's name. This may lead to a content spoofing or cross-site scripting (XSS) attacks depending on the capability of the receiver's mail client.