This past weekend, Litecoin encountered a bug that permitted an attacker to move digital assets to a decentralized exchange, leading to a network reorganization—a process known as a ‘reorg’—to thwart exploitation of this new vulnerability. This procedure effectively erased the erroneous transactions caused by a security lapse in the MimbleWimble Extension Block (MWEB) privacy feature, as detailed by Litecoin’s official X account on Saturday.
With blocks generated approximately every 2.5 minutes, a 13-block reorganization rewrote about 30 minutes of transaction history. Consequently, miners adopted a version of Litecoin’s blockchain that did not include the exploited bug. The zero-day vulnerability led to a denial-of-service attack affecting major mining pools and enabled the attacker to ‘peg out’ coins using an invalid MWEB transaction that could be exchanged on third-party decentralized exchanges.
Although the perpetrator was ultimately halted, they had leveraged an undisclosed flaw in the network’s privacy feature. Litecoin’s team issued an apology via X on Monday for deleting communications post-reorg and attempting humor regarding these events. The opt-in privacy feature of MWEB, alluding to ‘Harry Potter,’ was first proposed in 2019.
In a since-deleted X post, Litecoin claimed that its network infrastructure operated smoothly throughout the reorganization, asserting that faulty transactions were naturally removed as if they never occurred. However, security expert Taylor Monahan cautioned against trivializing such technical issues that put users’ funds at risk. Previously, Litecoin had compared itself to Solana, which experienced network congestion and performance issues in January 2025.
Aurora Labs CEO Alex Shevchenko suggested the attack might have been coordinated and noted potential exposure for NEAR Intents, a multi-chain protocol, at about $600,000. He also raised questions regarding whether some miners had already patched the vulnerability with updated software.
Reorganizations are feasible on proof-of-work networks like Bitcoin; the longest in its history involved a rollback of 53 blocks in 2010 due to a faulty transaction that generated an astronomical sum of Bitcoin, which was later nullified. On Monday, Litecoin ranked as the 25th largest cryptocurrency by market capitalization, valued at $4.2 billion, according to CoinGecko. The digital asset peaked near $410 five years ago and had recently traded around $55.35—a slight decrease of about 1% over the past day.