Many computer science curricula include a class or at least a lecture on disasters caused by software bugs, such as the Therac-25 incidents or Ariane 5 Flight 501. Indeed, Wikipedia has a list of software bugs with serious consequences, and a question on StackOverflow addresses some of them too.

We study the failures of the past so that we don't repeat them, and I believe that rather than ignoring them or excusing them, it's important to look at these failures squarely and remind ourselves exactly how the mistakes made by people in our profession cost real money and real lives.

By studying failures caused by uncaught bugs and bad process, we learn certain lessons about rigorous testing and accountability, and we make sure that our innocent mistakes are caught before they cause major problems.

There are kinds of less innocent failure in software engineering, however, and I think it's just as important to study the serious consequences caused by programmers motivated by malice, greed, or just plain amorality. Thus we can learn about the ethical questions that arise in our profession, and how to respond when we are faced with them ourselves.

Unfortunately, it's much harder to find lists of these failures--the only one I can come up with is that apocryphal "DOS ain't done 'til Lotus won't run" story.

What are the worst examples of moral failure in the history of software engineering?