That's a tricky question, because the answers are "yes" and "any number of locations." Cyclocross frames aren't magic - they're just like any other bike frame and can break for numerous reasons, either because of specific crash damage, a flaw in manufacturing or both. They're normally a bit tougher than your average road bike but not as tough as your average mountain bike. You've got to consider the riding conditions though and really dozens of other factors. This isn't something that you can make a broad generalization about other than "every frame can break."