Litecoin said a zero-day bug in its MimbleWimble Extension Block (MWEB) module affected unpatched mining nodes, causing a denial-of-service attack that disrupted major mining pools, enabled invalid MWEB transactions, and led to a 13-block chain reorganization that reversed the activity. Litecoin said valid transactions were unaffected, a patch has been released, and normal operations resumed. The Litecoin Foundation described the incident as a zero-day exploit, but the litecoin-project GitHub repository indicates the related consensus vulnerability was privately patched between March 19 and March 26, more than four weeks before the weekend attack.