An issue was discovered in Open-Xchange OX App Suite before 7.8.2-rev8. Script code within hyperlinks at HTML E-Mails is not getting correctly sanitized when using base64 encoded "data" resources. This allows an attacker to provide hyperlinks that may execute script code instead of directing to a proper location. Malicious script code can be executed within a user's context. This can lead to session hijacking or triggering unwanted actions via the web interface (sending mail, deleting data etc.).