[teddyh]

Many years ago, terminal emulators used to allow keyboard rebindings via escape codes. This is why it was then common knowledge to never “cat” untrusted files, and to use a program to display the files instead; either a pager, like “less”, or a text editor.

[jclulow]

I believe there were even more substantial issues in some terminal emulators, where escape sequences could write to arbitrary files or even execute programs. I think it's still very reasonable advice to avoid dumping arbitrary bytes into the terminal stream, even if only to avoid screwing up the state of the terminal.

[m3047]

It some cases it was possible for the server to use escape sequences to "read back" parts of what the terminal displayed.