At the start of the week, the BTC Core team encountered a bug in the code of the coin that allows miners sabotage the Bitcoin network by making double spending operations.
The programmers’ team warns that there is little chance of a chainsplit to happen. During a fork, all operations on the network can basically be reversed significantly after their initial confirmation. So, the researchers warned that within a week or two some transactions may well be reversed.
When a fork takes place, two or even more copies of one chain can exist and they will be similar to the point when they split and the codes each start going their own way.