Ask HN: What are the chances the NSA backdoored the Java/jvm platform?

If you take Java bytecode to be the attack surface, it is probably less likely than that a complex, microcode-based CPU instruction set contains a back door because it is hard to smuggle a multi-instruction side effect into an open source bytecode interpreter. Other attacks like an undocumented jni call are also difficult to conceal. That leaves things like network libraries, and most of those are an interface to protocols, leaving not much room for shenanigans, IF the source is available and build-able.

Adding a backdoor to open source software is no easy task...

Depends on whether you're talking about an OpenJDK you compiled yourself, or an official binary distribution.

The latter would be much easier for someone to backdoor.