source: https://www.securityfocus.com/bid/34688/info
Flat Calendar is prone to an HTML-injection vulnerability because it fails to sufficiently sanitize user-supplied data.
Attacker-supplied HTML or JavaScript code could run in the context of the affected site, potentially allowing the attacker to steal cookie-based authentication credentials and to control how the site is rendered to the user; other attacks are also possible.
"><script>alert("ZoRLu")</script>