On Friday and Saturday, a series of events unfolded as a 13-block chain reorganization occurred on the Litecoin network, effectively rewinding 32 minutes of activity after attackers leveraged a vulnerability in the Mimblewimble Extension Block protocol. The exploit, which was classified as a zero-day by the Litecoin foundation, was addressed through a private patch between March 19 and 26, with a subsequent release of Litecoin Core v0.21.5.4 containing crucial security updates.
Researchers, however, have pointed out discrepancies in the timeline of events, suggesting that the vulnerability was known and patched a month prior to the attack, but the fix had not been publicly disclosed or mandated for all mining pools. This created a window of opportunity for attackers to target unpatched nodes, resulting in a denial-of-service attack that allowed invalid transactions to slip through. The attack was eventually mitigated as the network's longest valid chain corrected the invalid transactions, but not before a 13-block reorganization was initiated to reverse the effects.
Prominent researchers have raised concerns over the handling of the exploit, citing the potential for similar attacks on other networks and the need for more effective communication and coordination among developers and mining pools.