A long, long time ago, it was literally possible to stuff the command buffer of a “dumb terminal” using ESC sequences and spoof keyboard input. So yeah, don’t count on ’cat’ being safe if your terminal isn’t!

I did this in 1985 on SOROC terminals we had in my first job out of college. However, it depended on the dip switch settings that were under a little door on top of the keyboard.