An issue was discovered in Open-Xchange OX App Suite before 7.8.1-rev14. Adding images from external sources to HTML editors by drag&drop can potentially lead to script code execution in the context of the active user. To exploit this, a user needs to be tricked to use an image from a specially crafted website and add it to HTML editor areas of OX App Suite, for example E-Mail Compose or OX Text. This specific attack circumvents typical XSS filters and detection mechanisms since the code is not loaded from an external service but injected locally. 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.). To exploit this vulnerability, a attacker needs to convince a user to follow specific steps (social-engineering).