A blockchain reorganization attack refers to a chain split, where nodes receive blocks from the new chain while the old chain continues to exist.
May 25, Ethereum Beacon Chain Suffers Seven-Block Reorganization And exposed to advanced security risks called chain organizations. Validators on Eth2 (Consensus layer upgrade now) Beacon chain becomes out of sync after client update promotes specific client. However, in the process, validators on the blockchain network got confused and did not update their clients.
A seven-block reorganization means that seven blocks of transactions are added to the fork that is eventually discarded before the network finds out that it is not the canonical chain. Therefore, if some node operators are faster than others, a blockchain reorganization will occur. In this case, the faster nodes won’t be able to agree on which block should be processed first, and they’ll keep adding blocks to their chain, leaving the shorter chain behind when the next block is created .
For example, miners X and Y may find a valid block at the same time, but because the block is peer-to-peer networkpart of the network will see X’s block first, then Y’s block.
If two blocks are of the same difficulty, there will be a tie and the client will have the option to choose randomly or to choose the previously seen block. When a third miner Z creates a block on top of X or Y’s block, the tie is usually broken and the other block is forgotten, causing the blockchain to reorganize.
In the case of Ethereum’s beacon chain reorganization, the latest node was about 12 seconds faster than the validator who didn’t update the client at block 3,887,074. An Ethereum chain reorganization occurs when an updated client submits the next block before the remaining validators. This leaves validators confused about who should commit the initial block.
According to Ethereum core developer Preston Van Loon, the reorganization of the Ethereum blockchain is due to the deployment of the Proposer Boost fork decision, which has not yet fully rolled out to the network. Furthermore, this reorganization is an important separation of newer and outdated client software, not a sign of a wrong choice.