It's much worse than that because of the complexity around JITs, behavior of hardware and speculative execution. Proper sandboxing is really hard, and I suspect

It's much worse than that because of the complexity around JITs, behavior of hardware and speculative execution. Proper sandboxing is really hard, and I suspect that if people really want security they would disable JIT in general. Even simple ones like pcre2. Personally I have disabled Firefox's JIT (I believe it's called ion in the settings, but correct me if I misremember) for a few years now. I've never had any trouble with any websites so far. It's not instant loading, but it's close enough. ... but I don't know if I would lump bytecode with JIT. Bytecodes don't need or use RWX execute segments, for example. Lots of your favorite JITs do, for speed.