X-Cart 5.2.23, 5.3.1.9, 5.3.2.13, and 5.3.3 is vulnerable to Remote Code Execution

X-Cart 5.2.23, 5.3.1.9, 5.3.2.13, and 5.3.3 is vulnerable to Remote Code Execution. This vulnerability exists because the application fails to check remote file extensions before saving locally. This vulnerability can be exploited by anyone with Vendor access or higher. One attack methodology is to upload an image file in the Attachments section of a product catalog, upload a .php file with an "Add File Via URL" action, and change the image's Description URL to reference the .php URL in the attachments/ directory.