There's a whole genre of fiction about scientists turning themselves into monsters through failed experiments. Neither Cronenberg's film nor the Hulk films were directly referencing one another; they were both simply entries in a much larger genre.
According to Stan Lee, the inspirations for the Hulk included Jekyll & Hyde and Boris Karloff's version of Frankenstein's Monster. So we're talking about influences from 1930s movies based on 19th-century novels.
Also, I don't get why the original poster would single out the Cronenberg remake of The Fly, since the original 1958 film of that name had the same storyline he specifies, a screwed-up experiment turning a scientist into a monster.
I'll say what I always say in threads like this: If something in one recent movie or show reminds you of something in another relatively recent movie or show, don't assume one copied the other, because it's vastly more likely that they were both influenced by something even earlier, probably something stretching back generations. It's the nature of human creativity that it includes recurring themes.