51% Attack

In a sentence

A 51% attack becomes possible when one actor controls most of a proof-of-work network's hashing power.

• A 51% attack becomes possible when one actor controls most of a proof-of-work network's hashing power.
• During the 51% attack, the attacker reorganized recent blocks and reversed selected transactions.
• Small networks may face greater 51% attack risk when rentable hash power is readily available.
• A 51% attack cannot arbitrarily create coins, but it can disrupt transaction finality.
• The exchange increased confirmation requirements after reports of a possible 51% attack.