According to a study commissioned by the Defense Advanced Research Projects Agency (DARPA), the blockchain technology underlying cryptocurrency might not be so decentralized and immutable after all. The in-depth study, which was conducted by Trail of Bits, uncovers how a very small number of participants can get excessive control over the entire ecosystem.

Over the last half-decade, 60% of the net global bitcoin traffic has been controlled by only three Internet Service Providers, and only 4.5% of bitcoin owners control over 85% of the entire crypto pool. The report, however, doesn't disclose any vulnerability in the cryptographically secure blockchain network, but instead highlights the weaknesses in the systems overseeing it.

Systemic flaws and vulnerabilities were highlighted in the report — for instance, protocol traffic is unencrypted, opening the doors for man-in-the-middle attacks, and 21% of the nodes run an old version of the bitcoin core client that is susceptible to attacks. Experts talking to NPR, however, feel the blockchain ecosystem will eventually rise above these flaws.