[127]

That doesn't make much sense as note on and note off messages are very simple and you can't insert arbitrary bytes with them, unless maybe you use some very particular run mode.

[bluGill]

Note on/off are just messages. We by convention map them to notes, but note 69 is A-440 on most keyboards, but you could see note 69 and play a C instead (this is somewhat common - have the computer transpose so you can play with others who play the music in a different key - better players can do this in their head but it is not a universal skill even with great players)

There is no reason you can't take a sequence of notes and do something else - pop up a root window for example. It isn't normally done because it would confuse everyone for no reason. (IIRC The original MIDI spec from the 1980s didn't have conventions of nearly as much and some midi devices did really weird things from note commands)

[stavros]

I think the GP's point is that the code that interprets simple note on/off messages is unlikely to be vulnerable to any kind of RCE.

[dhosek]

I also wish I had a pony. Wishes don’t need to make much sense.