MIT Technology Review: Once hailed as unhackable, blockchains are now getting hacked

More and more security holes are appearing in cryptocurrency and smart contract platforms, and some are fundamental to the way they were built.

Blockchains are particularly attractive to thieves because fraudulent transactions can’t be reversed as they often can be in the traditional financial system. Besides that, we’ve long known that just as blockchains have unique security features, they have unique vulnerabilities. Marketing slogans and headlines that called the technology “unhackable” were dead wrong.