AzuraCast: Path Traversal in `currentDirectory` Parameter Enables Remote Code Execution via Media Upload

AzuraCast is a self-hosted, all-in-one web radio management suite. Prior to version 0.23.6, the currentDirectory request parameter in the Flow.js media upload endpoint (POST /api/station/{station_id}/files/upload) is not sanitized for path traversal sequences. When combined with a local filesystem storage backend (the default), an authenticated user with media management permissions can write arbitrary files outside the station's media storage directory, achieving remote code execution by writing a PHP webshell to the web root. This issue has been patched in version 0.23.6.