Litecoin's 13-block reorg traced to a month-old private patch that never reached all…

Litecoin suffered a 13-block chain reorganization after attackers exploited a vulnerability in its Mimblewimble Extension Block (MWEB) protocol, rewinding roughly 32 minutes of on-chain activity. The Litecoin Foundation initially described the incident as a zero-day attack, but public GitHub commit history contradicts that framing.

Researchers, including SEAL911's bbsz, found that the core consensus bug was privately patched between March 19 and 26 — about four weeks before the exploit. A separate denial-of-service vulnerability was patched only on the morning of April 25, the day of the attack. Both fixes were bundled into Litecoin Core v0.21.5.4 after the attack had already begun.

The gap between private patching and full network deployment appears to have been the attack vector. Some mining pools ran updated code while others remained on the vulnerable version. Blockchain data…