51% Attack
Also known as: Majority Attack, Hashrate Attack
An attack where a miner or group controls majority of hashrate, allowing double-spend and censorship.
A 51% Attack occurs when a single miner or mining coalition gains control of more than 50% of the network’s hash power in a Proof-of-Work blockchain. This gives them the ability to delay or censor transactions, reorder blocks, or execute double-spending attacks. While they can’t create coins out of thin air or change protocol rules, these attacks undermine trust. Mitigation strategies include decentralizing mining power, implementing responsive forks, or transitioning to Proof-of-Stake consensus.