Seems like Major increment to me. But! If the fix is breaking some previous undefined behaviour to work correct then I think Minor with relnote. But! If the code is not in wide use, bump Patch and move on.
Seems like Major increment to me. But! If the fix is breaking some previous undefined behaviour to work correct then I think Minor with relnote. But! If the code is not in wide use, bump Patch and move on.