[hashmash]

The Java runtime isn't any more inherently insecure than the JavaScript runtime, and JavaScript seems to work just fine for the web.

The key reason why applet security failed was because it gave you the entire JDK by default, and so every method in the JDK needed to have explicit security checking code in place to restrict access. The model was backwards -- full control by default with selective disabling meant that every new feature in the JDK is a new vulnerability.

[bloppe]

Just look up "Java applet sandbox escape". There were tons of ways to do it. Here are some [0]. Then there's the coarse-grained permissions that were essentially useless to begin with.

[0]: https://phrack.org/issues/70/7

[hashmash]

Yes, I'm familiar with these. Many of the earliest problems were to due bugs in the verifier, and there were several different vendors with their own set of bugs. The bulk of these problems were identified and resolved over 25 years ago.

Most of the later problems are due to the fact that the API attack surface was too large, because of the backwards SecurityManager design. And because it existed, it seems there was little incentive to do something better.

Once the instrumentation API was introduced (Java 5), it made it easier to write agents which could limit access to APIs using an "allow" approach rather than the awful rules imposed by the SecurityManager. Java 9 introduced modules, further hardening the boundaries between trusted and untrusted code. It was at this point the SecurityManager should have been officially deprecated, instead of waiting four more years.

Going back to the earlier comment, the problem isn't due to the runtime being somehow inherently insecure, but instead due to the defective design of the SecurityManager. It hasn't been necessary for providing security for many years.