Litecoin Network Reorgs 13 Blocks After MWEB Exploit

The Litecoin network underwent a significant 13-block reorganization over the weekend of April 25-26, 2026, after attackers exploited a vulnerability in its MimbleWimble Extension Blocks (MWEB) privacy protocol, combined with a denial-of-service (DoS) attack on major mining pools. The incident, which affected unpatched nodes and briefly allowed invalid transactions, was resolved without any reported loss of user funds, according to the Litecoin development team.

The disruption began late Friday when a flaw in MWEB's input validation enabled malformed transactions on nodes running outdated software. These nodes accepted invalid peg-outs, moving Litecoin (LTC) to decentralized exchanges (DEXs) and cross-chain swap protocols without proper authorization. The DoS attack targeted mining pools that had applied recent updates, temporarily reducing their hashing power and allowing the vulnerable chain to extend for about 32 minutes, or roughly 13 blocks at Litecoin's typical 2.5-minute interval. This created a temporary fork, with block times stretching to over three hours during the affected sequence.

Once the DoS subsided, nodes with updated software regained dominance, triggering the...