The Cuba JPA web API enables loading and saving any entities defined in the application data model by sending simple HTTP requests. Prior to version 1.1.1, the input parameter, which consists of a file path and name, can be manipulated to return the Content-Type header with text/html if the name part ends with .html. This could allow malicious JavaScript code to be executed in the browser. For a successful attack, a malicious file needs to be uploaded beforehand. This issue has been patched in version 1.1.1. A workaround is provided on the Jmix documentation website.

XSS in the /download Endpoint of the JPA Web API