The old versions of EXIF Viewer Classic contain a cross-site scripting vulnerability caused by improper handling of EXIF meta data. When an image is rendered and crafted EXIF meta data is processed, an arbitrary script may be executed on the web browser. Versions 2.3.2 and 2.4.0 were reported as vulnerable. According to the vendor, the product has been refactored after those old versions and the version 3.0.1 is not vulnerable.
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.