> Then, afer some magic character was printed, their terminal would start interpreting the rest of the output as commands. The commands were gibberish, nothing happened, but very dangerous nonetheless.

By commands, you probably mean "escape sequences", which are not the same as running executables and isn't very dangerous.

If a terminal actually executed commands based on data printed to stdout, that would be a very significant vulnerability. It seems far more likely that the gibberish you're talking about is the usual mess of escape sequences.