On Tuesday, Bitcoin Core released client update 0.16.3 to address a major vulnerability in Bitcoin software. In the announcement, Bitcoin Core cited a denial-of-service (DoS) vulnerability discovered in its client versions 0.14.0 to 0.16.2. The author of the post, Wladimir J. van der Laan, recommended that all affected clients be updated ASAP.
The bug extends to many other clients running various Bitcoin-derived blockchains as well, because many altcoin blockchains rely on software derived from the Bitcoin Core client. In case that word jumble lost you, let me break it down:
Bitcoin is a blockchain. A client is the software that allows you to interact with a blockchain. Altcoins are cryptocurrencies that aren't Bitcoin, many of which run on blockchains that have forked from the Bitcoin blockchain. Many of these blockchains use modified versions of Bitcoin-specific clients.
To be clear, the bug was not present in Bitcoin's underlying code – just the client software, so not all altcoins were affected. Some altcoin blockchains rely on clients that are not based in the versions of Bitcoin Core client software affected by the bug, but many, including Litecoin and Bitcoin Cash's Bitcoin ABC, are built on the affected software and were affected. Litecoin announced Tuesday that it had patched the vulnerability, as did Bitcoin ABC.
Bugs happen. This is nothing new or unique to Bitcoin, but the scope of the near miss makes it notable. Due to the overwhelming dominance of Bitcoin Core within the mining community, the attack still would have affected an estimated 95 percent of Bitcoin nodes.
Emin Gün Sirer tweeted that had the bug been exploited, "it would have crashed nodes and disconnected the network." He told Motherboard that the attack, which could have been executed by miners, would have cost less than $80,000.
In other words, it could've been a Bitcoin Apocalypse. What then would the world's bitcoin maximalists have done?
Perhaps they'd have found comfort in the warm embrace of cryptoman's most faithful (furry, and funny) friend, Dogecoin.
Disclaimer: does not endorse Dogecoin.