Litecoin Just Reorged 13 Blocks. A Zero-Day Pegged Invalid MWEB Coins Out to DEXs.

April 25, 2026

The Litecoin Project confirmed a 13-block chain reorganization on April 25, 2026. Blocks 3,095,931 through 3,095,943 were replaced to undo invalid MWEB peg-outs that had been created by mining nodes running unpatched software. A zero-day exploit had allowed invalid coins to be pegged out into DEXs. F2Pool mined all blocks on the winning chain.

13-block reorg: blocks 3,095,931 through 3,095,943 replaced
Last common ancestor: block 3,095,930, mined by AntPool at 06:39:06 UTC
Cause: zero-day exploit — MWEB input/output accounting allowed invalid kernel sum
Invalid MWEB coins were pegged out to decentralized exchanges before the fix
F2Pool mined 100% of the corrected winning chain (all 13 replacement blocks)
Consensus pause: 52 min 15s gap between blocks 3,095,931 and 3,095,932
Mempool flush: block 3,095,944 cleared 1,198 transactions in 414 KB
Emergency patch: Litecoin Core v0.21.5.4 released same day by Loshan
All valid transactions during the window remain in the canonical chain

What The Litecoin Project Confirmed

A zero-day bug caused a denial-of-service attack that disrupted major mining pools. Mining nodes that had not been updated allowed an invalid MWEB transaction that pegged coins out to third-party DEXs. A 13-block reorg reversed those invalid transactions — they will never be included in the main chain. All valid transactions during that period remain unaffected. The bug is described in the v0.21.5.4 release notes as 'an input validation issue that could allow the MWEB kernel sum to become unbalanced.' The fix 'corrects MWEB input/output accounting going forward.'

The 13 Reorged Blocks (On-Chain Reconstruction)

Block 3,095,930 (AntPool, 06:39 UTC) was the last common ancestor. The winning chain ran entirely on F2Pool: height 3,095,931 at 06:50 (461 txs), 3,095,932 at 07:42 (+52 min gap, 125 txs), 3,095,933 at 07:48 (187 txs), 3,095,934 at 08:11 (890 txs), 3,095,935 at 08:17 (227 txs), 3,095,936 at 08:35 (469 txs), 3,095,937 at 08:42 (494 txs), 3,095,938 at 08:44 (113 txs), 3,095,939 at 08:51 (276 txs), 3,095,940 at 08:56 (168 txs), 3,095,941 at 09:14 (832 txs), 3,095,942 at 09:31 (1,147 txs), 3,095,943 at 09:35 (255 txs). Total elapsed: 2 hours 45 minutes for 13 blocks — 5.1× slower than the 32.5-minute target. The first post-reorg block (3,095,944) contained 1,198 transactions flushing the accumulated mempool backlog.

Full interactive article with on-chain data available at ltc.supply/news/litecoin-13-block-reorg-april-2026