I have read some stories where various airgapped systems were "compromised" in some way (microphone picking up CPU harmonics,etc). See here for example: https://thestack.com/security/2016/06/24/even-speakerless-ai... Obviously those are fringe cases and not practically exploitable outside of a specific environment today.

What I think the danger with a super intelligent AI is being able to correlate massive amounts of data to see patterns we miss or things to try, and never being bored. Look at automated exploits today vs the old "hacking by hand". Brute force attempts not just on known patterns, but being able to create new tests and analysis.