In line with a recent ‘analysis report‘ published bv BitMex exchange, following the recently occurred hard-fork earlier on 15th May, Bitcoin Cash [BCH] seems to have experienced a two-block chain reorganization leading to about 3,392 BCH [around $1.35 Mln at the reporting time] double spend.
As per the report, the recent Bitcoin Cash ‘hard fork‘ experienced 3 interlinked issues. Firstly, an apparent bug evidently exploited by a hacker just after the hard -fork. The hacker “broadcasted transactions that met the mempool validity conditions but failed the consensus checks.” Miners attempted to generate blocks with aforesaid transactions weren’t able to, instead generating empty blocks.
The empty blocks reportedly resulted in concern among miners that “might have tried to mine on the primary non-hard fork chain, inflicting a consensus chainsplit.”
The 3rd drawback was that the consensus chainsplit allegedly prevented a system meant to recover funds accidentally sent to ‘SegWit’ addresses from functioning. In line with ‘BitMex‘ analysis, “this failure might have resulted in a deliberate and coordinated a pair of blockchain re-organisation.”
Adding further, the report claims:
“Based on our calculations, about 3,392 Bitcoin Cash might had been successfully double spend in an orchestrated transaction reversal. However, the sole victim with regard to these double spent coins could have been the primary ‘thief.’”
As BitMex analysis reports, the above mentioned 3 issues within the hard fork resulted in 25 transactions ‘transferring 3,392 Bitcoin Cash’ not being enclosed within the reorganized chain, that constitutes a double spend.