I might be nitpicking, but I disagree with Raymond Chen here.

Regarding his example, IMO, the process of saving a file has a platonic security abstraction, it is a very limited computation engine. When one is able to escape this abstraction, it is a security concern.

The distinction between a security bug and non security bug is very subtle.

An example how this violation may happen in real life. Assume a filesystem that may contain long filenames, an attacker may control it and cause remote execution. Another scenario may be a site that tells you to see an easter egg in notepad by fire up notepad and save a file named <payload>, which will do some trick and will also run arbitrary code on your machine.