Confirmation process: Cryptocurrencies require confirmation from multiple nodes in the network before a transaction can be considered valid and added to the blockchain.
Race condition: A double-spend attack exploits a race condition in which a conflicting transaction is broadcasted before the original transaction is confirmed.
Attack vectors: Double-spend attacks can occur through various attack vectors, including 51% attacks, Finney attacks, and Vector76 attacks.
51% attack: A 51% attack is when an attacker controls more than 50% of the network's hash rate, allowing them to control the confirmation process.
Finney attack: A Finney attack is when an attacker creates a conflicting transaction in advance and includes it in a block they have mined, allowing them to broadcast it immediately after the original transaction.