backpack/crud: HasUploadFields keeps the attacker-supplied file extension — public-disk uploads of `shell.php` reach the webserver

backpack/crud provides Create, Read, Update & Delete (CRUD) functions for Backpack, a collection of Laravel packages that help users build custom administration panels. From 6.0.0 until 6.8.14 and 7.0.38, HasUploadFields methods uploadFileToDisk and uploadMultipleFilesToDisk, used through CrudTrait, and the withFiles() path through FileNameGenerator do not internally reject server-executable file types. An authenticated administrator can achieve remote code execution by using an upload-enabled CRUD field without mimes: and mimetypes: validation when the public disk is web-accessible through php artisan storage:link and the web-server and PHP-FPM configuration executes the stored extension. The legacy path preserves an accepted extension and the newer path derives an extension without blocking dangerous types. The package-level restriction is defense in depth and does not replace application-level upload validation. This issue is fixed in versions 6.8.14 and 7.0.38.