It is defined in the article the first time it is used in the text.
Maybe they read your comment and fixed it?
Perhaps so! I didn’t see it defined anywhere earlier.
These days people use "RCE" for local code execution.
I would clarify that as running code somewhere you don’t already control. The classic approach would be a malformed request letting them run code on someone else’s server, but this other pull-based approach also qualifies since it’s running code on a stranger’s computer.