A vulnerability in the file upload functionality of the FlatPress CMS admin panel (version latest) allows an attacker to upload a file with a JavaScript payload disguised as a filename. This can lead to a Cross-Site Scripting (XSS) attack if the uploaded file is accessed by other users. The issue is fixed in version 1.4.dev.
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.