Both mistakes are amazingly easy to fall into, unfortunately.
Using software released in 2004 without patching up vulnerabilities is probably a more significant problem.
I was ready to give up on JavaEE around version 1.4, but it's so much fun to program JavaEE now. A lot more like TurboGears or RoR (lots of meta-programming and default "scaffolding").
I mean, this is a classic example of badly configured filesystem permissions.
You deploy Play apps inside an application container (like JBoss, Tomcat, Jetty, etc...)
Vert.x is based on Netty and thus it is not running on an application container.
I'd say that Vert.x or Netty based apps are more safer - from this point of view, but there may be some other kind of vulnerabilities for them..
Also, it's important to note that the owner of the VPS instance didn't took proper precautions: "I overlooked the deployment of the web console and HTTP Invoker and I paid for that". If you go by the book and do everything right JBoss and other application containers are safe to use.