First of all, WTH do you mean by "universal"? Do you mean "true for everyone"? Or "true across all logically possible worlds?"
I guess it doesn't matter, because in either case the answer is clearly "yes".
Usually when someone with no philosophy training comes to this conclusion, its usually just hyper-skepticism. First of all, hyper-skepticism is not a good position, because it doesn't properly understand the meaning of the word "knows". Second, even if hyper-skepticism were true, its merely a thesis about what we can know, not what propositions are true.
Let this calm your fears: the locution "x knows y" does not necessitate that x knows y beyond any shadow of a doubt whatsoever.
Maybe we don't know anything beyond any shadow of a doubt, but who gives a crap? We still know lots of stuff, because knowing something beyond a shadow of a doubt is not necessary for knowing it!