The thoughtbot paperclip gem before 4.2.2 for Ruby does not consider the content-type value during media-type validation, which allows remote attackers to upload HTML documents and conduct cross-site scripting (XSS) attacks via a spoofed value, as demonstrated by image/jpeg.
Improper Neutralization of Input During Web Page Generation 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.