But it wasn't really confirmed in manga. Yes, some fans tried to show evidence of Zoro coc, but we still cannot be sure about it. We don't have question about Luffy coc, case it was showed before time skip.
In fact only Nami pretend to be coc user, and that's from Jinbei. But I doubt that Nami have coc and I believe that Zoro have coc, but right now it wasn't confirmed.