"A searching or sorting utility function is called with an invalid pointer argument, even if the number of elements is zero"
But because of broad choices like:
"The execution of a program contains a data race"
"An object is referred to outside of its lifetime"
These are essentially categories of mistake we know programmers make, and in C the result is... Undefined Behaviour. No diagnostics, no exit, no errors, just throw your hands in the air and give up, anything might happen.
My personal memorable one was bit shifting 32bit values by varying amounts, and our test vectors all failing after a compiler update, because some of the shifts were by 32. Undefined behaviour.