Japanese doesn't really have 'profanity' in the European sense. There aren't words that are vulgar or censorable by virtue of being that word. There are words that are vulgar or censorable because of the meaning they have (eg words relating to sexual anatomy and so on), but there's nothing equivalent to English 'shit' that's considered censorable largely by convention, and possible to rephrase some other, less vulgar way.
Thus, くそ by virtue of its meaning is somewhat vulgar, but it's not censorable. The reason it's matched in translation with English words like 'shit' (and 'fuck' when used as a frustrated exclamation) is because Japanese simply has nothing that's a closer equivalent - くそ appears in the same situations as those English expressions, but it lacks many of the connotations that the English words are often specifically used to convey. I suppose you might say that くそ covers pretty much the full range of both 'crap' and 'shit', with the core meaning probably somewhat closer to 'crap' as it lacks the stronger vulgarity of 'shit' - you'll hear eight-year-old kids say it on TV and no one bats an eye. Still, depending on the circumstances, it might be more natural to translate it as 'shit' (or 'fuck') because of the way English usage works.