I've been updating some MUDs to work on "modern" OS's, and have run into so many use-after-free issues that it's almost become a hobby fixing them.
Do you hang out in the Mud Coder's Guild Slack at all? You might find it interesting: https://mudcoders.com/join-the-mud-coders-guild-6770301ddcbd...
I don't, but I was named by name in "Playing MUDs on the Internet" :)
I have copies of Epic, SillyMUD, Phoenix, and now Kaos.