Vitalik Buterin urged the community to prepare for a potential 51% attack on EthereumA 51% attack in the context of Proof-of-Stake is a situation in which an attacker controls more than 50% of all coins blocked to participate in the validation of network blocks. This results in opportunities for:
- manipulation - validate only transactions favorable to attackers and reject or delay others;
- double-spending - performing the same transaction multiple times, defrauding the network;
- history rewriting - make changes to already confirmed blocks, creating alternate chains;
- сensorship - block certain transactions or addresses