Minecraft, like any software, is subject to security vulnerabilities. You can find information on how to mitigate or patch notorious issues here.
📄️ Minecraft Server Bot Scanners
📄️ No Route to Host
The java.net.NoRouteToHostException: No route to host error is one of a few known errors that appear when you’ve been infected with malware through one of the plugins you’ve installed on your Bukkit based server. You’ll normally find infected plugins on sites that leak premium plugins or re-host them away from the authors official source, though the official source can be compromised on rare occasions.