A man monitors a blockchain network's status and activity in a high-tech control room
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A network security failure in which a single miner or coordinated group gains control of more than half of a blockchain’s total mining or staking power, allowing them to block new transactions, reverse recent ones, or double-spend coins.
Applied: Ethereum Classic suffered several confirmed 51% attacks between 2019 and 2020, prompting exchanges to raise the confirmations required before crediting deposits.
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