I think we've seen the Borg attacked by genetics in planted drones, and uploaded viruses. Each time they had limited and localized effect that the Borg found and isolated from the rest of the collective. Even the Queen was local. Once damaged or killed, she was downloaded and recreated. Repaired and regenerated. Adaption is the name of the game and the Borg always learn from a successful tactic and wouldn't hesitate to self destruct a Cube and take counter measures or precautions against a similar attack.