According to CoinMeta, Wu said that it has been learned that the established POW public chain Ravencoin has a serious consensus vulnerability that has been actually exploited, causing some nodes to accept invalid blocks. The first known abnormal block appeared at height 4,487,776. Currently, 2 miners control the majority of the computing power with ravenminer and are mining a new chain that excludes the abnormal branches starting from this height. If this new chain becomes the main chain, there could be a deep reorganization of the network that would take about three days. Ravencoin recommends that exchanges temporarily stop RVN deposits and consider any transactions after block 4,487,775 to be at risk of rollback.