The great consensus cleanup is a new BIP suggested by developer Matt Corallo to address different issues in the current Bitcoin consensus, the new set of consensus changes aim at reducing complexity of Bitcoin implementations, improving worst-case validation times and fixing vulnerabilities like timewarp.
Feed for tag: timewarp-attack
A timewarp attack on Bitcoin allows malicious miners to game the timestamp system to allow them to increase the rate of block generation beyond what the blockchain meant it to be. This attack has been possible since 2012 and was demonstrated on the testnet.
This was dismissed as an unimportant issue for the past few years as it requires the majority of hashrate and is easily blocked once someone starts using it.