Yes. But failing at the intent of the protocol in the process. When a hacker exploits a buffer overrun to take control of a remote computer, the computer is following its prescribed mechanisms to the letter. But that's certainly not what the computer's owner wants it to be doing.
If adding blocks to a PoW chain had no cost then the chain wouldn't be functioning as its users desire - there'd be no canonical fork any more. It would fail to solve the Byzantine generals problem, which is fundamentally the purpose of cryptocurrency.