e107 CMS v3.2.1 - Upload Restriction Bypass with Path Traversal File Override

e107 CMS version 3.2.1 contains a critical file upload vulnerability that allows authenticated administrators to override arbitrary server files through path traversal. The vulnerability exists in the Media Manager's remote URL upload functionality (image.php) where the upload_caption parameter is not properly sanitized. An attacker with administrative privileges can use directory traversal sequences (../../../) in the upload_caption field to overwrite critical system files outside the intended upload directory. This can lead to complete compromise of the web application by overwriting configuration files, executable scripts, or other critical system components. The vulnerability was discovered by Hubert Wojciechowski and affects the image.php component in the admin interface.