"DOCX bluescreens Windows" is exactly how your hypothetical scenario would be described.
"Bush hid the facts" is described as a Notepad bug, even though it's a bug in a specific WinAPI function used by Notepad and thus would also affect other programs that used that function. It was discovered on Notepad, it became popular as a bug of Notepad, and so it's considered a Notepad bug.
It'd be kind of crazy if there was something inherent to the TXT that when opened in any program made that bug occur! But the issue was with Notepad! Much more believable!
Windows bug would be acceptable too, or WinAPI bug :)
This isn't that complicated, I don't mind teaching y'all how to not write non-clickbait headlines
"Bush hid the facts" is described as a Notepad bug, even though it's a bug in a specific WinAPI function used by Notepad and thus would also affect other programs that used that function. It was discovered on Notepad, it became popular as a bug of Notepad, and so it's considered a Notepad bug.