In rclone serve restic, the WithRemote middleware fails to properly sanitize URL paths beginning with "../" or containing ".". Because path.Clean preserves leading parent directory components in relative paths, requests with leading traversal sequences bypass validation. On affected backends (such as WebDAV, FTP, SFTP, HTTP, and memory), an attacker with access to the REST endpoint can read, create, overwrite, or delete objects outside the configured root directory.