Temporary block withholding - selfish mining Fee sniping attack Goldfinger attack Bribery attack Feather forking If an already mined block has a really high transaction fee then a miner might decide to re-mine that block to claim the transaction gee. For example, if the attacker has 20% mining power and is going to try up to 2 blocks to re-mine then the likelihood of success is 4% but a miner does not want to take 4% chance of losing the mining fee.