The CUBA REST API add-on performs operations on data and entities. Prior to version 7.2.7, 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 7.2.7. A workaround is provided on the Jmix documentation website.
https://github.com/jmix-framework/jmix/security/advisories/GHSA-x27v-f838-jh93
https://github.com/cuba-platform/restapi/security/advisories/GHSA-88h5-34xw-2q56
https://github.com/cuba-platform/restapi/commit/b3d599f6657d7e212fdb134a61ab5e0888669eb1
https://docs.jmix.io/jmix/files-vulnerabilities.html#disable-files-endpoint-in-cuba-application