Double Spend Attack

When any transaction uses the same input as that of another transaction previously verified within the network, it is termed double-spending. Leading to the creation of a double-spend attack, where a user gains the ability to spend the cryptocurrency more than once.

Cryptocurrency projects that are still using Proof-of-Work (PoW) consensus mechanism are mainly subjected to the double-spend attack. While double-spend attack revolves around duplicating or faking the original transaction, reversal of a transaction is also possible using the attack.

There are several new double-spend attacks that have emerged over time. Some of the most common include the Finney attack, 51% attack, Race attack, and more. Since blockchain cannot prevent all double-spend attacks, it can always adapt to an improved and better consensus mechanism.