Following its hard fork on May 15, bitcoin cash (BCH) appears to have experienced a two-block chain reorganization resulting in a 3,392 BCH (about $1.35 million at press time) double spend. The claim was made in a report released by the research arm of cryptocurrency derivatives exchange BitMex on May 24.
Per the report, the recent BCH hard fork experienced three interrelated issues. Firstly, an apparent bug evidently exploited by an attacker right after the hard fork. The attacker was able to “broadcast transactions which met the mempool validity conditions but failed the consensus checks.” Miners attempting to produce blocks with said transactions were not able to, instead producing empty blocks.
https://cointelegraph.com/news/bch-may-have-sustained-13-million-double-spend-bitmex-research
