AEM's Cloud Service offering, as well as version 6.5.6.0 (and below), are affected by a stored Cross-Site Scripting (XSS) vulnerability that could be abused by an attacker to inject malicious scripts into vulnerable form fields. Malicious JavaScript may be executed in a victim’s browser when they browse to the page containing the vulnerable field.
https://helpx.adobe.com/security/products/experience-manager/apsb20-72.html