AEM versions 6.5.5.0 (and below), 6.4.8.1 (and below) and 6.3.3.8 (and below) are affected by a stored XSS vulnerability that allows users with 'Author' privileges to store malicious scripts in fields associated with the Inbox calendar feature. These scripts may be executed in a victim’s browser when they open the page containing the vulnerable field.
https://helpx.adobe.com/security/products/experience-manager/apsb20-56.html