A series of events unfolded over the weekend as a 13-block reorganization on the Litecoin network rewound approximately 32 minutes of activity after attackers leveraged a vulnerability in the Mimblewimble Extension Block protocol, enabling a denial-of-service attack against major mining pools. This allowed invalid transactions to bypass nodes that had not been updated, before the network's longest valid chain corrected them. The Litecoin Foundation announced that the bug had been fully patched and the network was operating normally by Sunday morning. However, security researchers have pointed out discrepancies in the timeline of events, suggesting that the vulnerability was known and patched privately a month before the attack, but the fix had not been publicly disclosed or mandated for all mining pools.
This created a window of opportunity for attackers, who appeared to be aware of which mining pools were running the patched code and which were still vulnerable. The attack involved a pre-funded wallet and a decentralized exchange, and the fact that the network automatically handled the 13-block reorganization once the denial-of-service attack stopped suggests that enough hashrate was running updated code to eventually overpower the attack.