I like the clarification:
Let me also touch this subject while talking security problems. This bug, the oldest so far in curl history, was a plain logic error and would not have been avoided had we used another language than C.
Otherwise, about 40% of all security problems in curl can be blamed on us using C instead of a memory-safe language. 50% of the high/critical severity ones.
Almost all of those C mistakes were done before there even existed a viable alternative language – if that even exists now.
I wonder whether some careful specifications and model checking could have found this.
As the article says, the problem was the logic. They had thousands of hours of model checking.
They had 1000s of hours of fuzz testing. Model checking means something different.