From what I have read, you aren't the only one. There are reports that this security update broke the front end on some themes. And a follow-up release is supposed to have gone out shortly after to fix it. I can't say for certain that it's your case. But it's cheap to check.
So before you touch anything else: go to Dashboard > Updates in your admin and see if there's a new WordPress update waiting there. If so, run it and check the shop front page again.
If nothing is waiting, or it's still white afterwards, post back and we go from there.
