It still makes it sound like the problem really is the other service that is letting a remote connection invoke some part of MS paint.
But why MS Paint? What functionality does it offer to another program to get called on specifically? And if this other service isn't calling on it specifically, what else can it be tricked into calling? And how many of those are also vulnerable to being stabbed in the back? The smaller interior holes are a problem, sure, but it seems like the CVE should be for the hull hole in that case.