Litecoin rolls back 13 blocks after MWEB bug; apologizes

Litecoin performed a 13-block reorganization after a zero-day vulnerability in its MimbleWimble Extension Block (MWEB) privacy layer allowed an attacker to move coins to a decentralized exchange and disrupt mining pools. Miners coordinated to adopt a chain that excluded the faulty transactions, effectively removing about 30 minutes of transaction history.

The exploit relied on an invalid MWEB transaction that some nodes running outdated software accepted. That acceptance let the attacker “peg out” coins from the privacy layer to a third-party decentralized exchange and created a denial-of-service condition affecting major mining pools. Litecoin blocks are produced roughly every 2.5 minutes, so reversing 13 blocks rewrote the sequence that contained the exploit.

The network’s account on X deleted several follow-up messages and issued an apology for posts that tried to use humor after the reorg. One deleted post described the reverted transactions as having gone “through the poop shoot.” On-chain investigator Taylor Monahan wrote that projects should avoid a casual tone when explaining technical issues that put users’ funds at risk.

Alex Shevchenko, CEO of Aurora Labs, estimated that the exploit created about $600,000 in potential exposure for NEAR Intents, a multi-chain protocol. He also raised questions about whether some miners were running patched software while others had not updated.

Reorganizations of competing chains are a known mechanism on proof-of-work networks to resolve conflicting blocks. The longest recorded reorganization on the largest proof-of-work network rolled back 53 blocks in 2010 after a faulty transaction produced an invalid issuance that was subsequently removed.

At the time of the incident, Litecoin’s market capitalization was about $4.2 billion and the token traded near $55. Developers and miners are checking node software versions to confirm the vulnerability has been patched across the network. Litecoin reported that network operations continued during the reorg and that the invalid MWEB transactions were removed from the adopted chain.