I think you're taking their choice of a single word a bit too seriously, and dare I say, personally. I don't think they're claiming to be the first to have ever discovered this attack vector, nor are they trying to steal credit from you. And while "novel" might not be the best word choice, in common parlance it need not mean "unique," and can just as well mean "unusual." In fact the dictionary definition of "novel" literally includes "unusual" ("new or unusual in an interesting way").