From en.secnews.gr
Two years ago (in 2018), a security researcher found one great vulnerability in Bitcoin Core. This is the software that powers the Bitcoin blockchain . The researcher reported the issue which was corrected , however he kept the information about the Bitcoin bug secret so that the hackers could not exploit it in any way.
The technical details were published two years later, a few days ago, after the same Bitcoin bug was discovered in cryptocurrency, based on an older version of the Bitcoin code, which has not received the update (patch).