Critical vulnerability in the main bitcoin software
On 19 September, Bitcoin Core team informed the public about the critical vulnerability in their main bitcoin software. Users who were using the new Bitcoin Core software release, were vulnerable for the critical bug which could exploit the double-spend vulnerability. Double spending means that a single coin is being spent twice.
Main idea behind the bitcoin network and payment system is to prevent double spending transactions. Bug was anonymously reported, and quickly patched with no signs that it has been exploited. This bug was particularly dangerous because almost 98% of users are using Bitcoin Core open-source software. Core team patched this bug immediately but still there is a need for the wider update. Statistic data shows almost 50% of network nodes is still to be updated. In the meantime, the stability of network is intact. Read the Bitcoin Core group full disclosure here