Adobe Experience Manager versions 6.5.21 and earlier are affected by a DOM-based Cross-Site Scripting (XSS) vulnerability that could be exploited by an attacker to execute arbitrary code in the context of the victim's browser session. By manipulating a DOM element through a crafted URL or user input, the attacker can inject malicious scripts that run when the page is rendered. User interaction is required for exploitation, as a victim must visit a malicious link or input data into a vulnerable web application.