Friend, you are looking confuse.
a^n b^n c^n are different from kleene closure. a^n b^n c^n is not context free because in CNF there is only stack data structure is used to compare the alphabet of string if required. Language is CNF only if there is two or less than alphabet need to compare. Here there are three alphabet whose number are need to compare in string. That is not possible through single stack.
If any thing feel wrong plz comment.