Multiple cross-site scripting (XSS) vulnerabilities in BigTree CMS through 4.2.18 allow remote authenticated users to inject arbitrary web script or HTML by uploading a crafted package, triggering mishandling of the (1) title or (2) version or (3) author_name parameter in manifest.json. This issue exists in core\admin\modules\developer\extensions\install\unpack.php and core\admin\modules\developer\packages\install\unpack.php. NOTE: the vendor states "You must implicitly trust any package or extension you install as they all have the ability to write PHP files.