The vulnerability in the mechanism of Bitcoin Cash consensus, able to fatally damage the network of the cryptocurrency, was found by Bitcoin Core developer Cory Fields. He wrote about it in a long post, again stirring up debates on the responsible disclosure of data about vulnerabilities of open source projects.

The problem was that the bug allowed to use the Bitcoin Cash network for self-enrichment, and Fields was afraid that if he told about the bug and someone used it, he would be accused of the attack.

The vulnerability found by Fields can be called a “chain-crushing bug”. Due to the lack of transaction verification, users of two versions of a code may find themselves in two incompatible blockchains. As a result, if a network is distributed in a certain way between nodes and users, it will make it very difficult or even impossible to agree on which transactions can be considered correct. This vulnerability, according to Fields, could divide Bitcoin Cash into two networks and as a result destroy the value of BCH.

Fields is working in an initiative on digital currencies at the Massachusetts Institute of Technology’s media lab, and his main work is focused on developing the Bitcoin Core client. The information revealed by Fields led to a new wave of criticism of the Bitcoin Cash project. Recently, the Bitcoin ABC team announced that it is preparing a number of updates that will be included in the hardfork scheduled for November.