It's possible but realistically it's not happening. Since the entire network validates things all simultaneously you would need something to affect every computer running nodes for bitcoin simultaneously, and this doesn't account for nodes that are offline at the time either. As soon as the majority of the nodes show that these transactions are invalid they will be rejected. The entire point of blockchain is that it's pretty much unhackable because there's no central point at which you can attack. The network is distributed across all of it's users, and that's what makes it strong.