Admidio is an open-source user management solution. In versions 5.0.6 and below, the eCard send handler uses a raw $_POST['ecard_message'] value instead of the HTMLPurifier-sanitized $formValues['ecard_message'] when constructing the greeting card HTML. This allows an authenticated attacker to inject arbitrary HTML and JavaScript into greeting card emails sent to other members, bypassing the server-side HTMLPurifier sanitization that is properly applied to the ecard_message field during form validation. An attack can result in any member or role receiving phishing content that appears legitimate, crossing from the web application into recipients' email clients. This issue has been fixed in version 5.0.7.

Admidio has an HTMLPurifier Bypass in eCard Message Allows HTML Email Injection