Yes, it stops there. Any scientific evidence to the contrary is controversial and anecdotal at best, not supported by a wider systematic body of evidence.
Human hearing stops at 20 kHz (in newborn babies, going downhill from there), just like we obviously cannot see UV light, unlike bees, for example. As to the latter, it is very instructive to look at images of what they actually see when they look at flowers, with details only visible in UV light shifted for us into the visible range. There is just a hard stop for us.
I don't consider the CD medium perfect, but frequency reproduction is not the problem, in my view. It does cut it awfully close to the theoretical limits of transparency, in terms of practical demands on filtering (a 48 kHz format would have been better), and in terms of bit depth. A more 'generous' format makes proper practical implementation easier and more forgiving, and may even add some theoretical gain in transparency, when it comes to bit depth.
On the other hand I am constantly astonished about the incredible and realistic resolution of fine detail from the CD format. And it can be on just a mindboggling level if reproduction through the rest of the chain allows it, as I also recently witnessed in Madfloyd's system especially on orchestral music (and from the same DAC that we have). The purity and ease of tone there was just astonishing as well. All from a plain Redbook CD file.