What does the minimum confirmations required for a deposit mean for the security of exchanges? For example, Coinbase requires 3 confirmations for Bitcoin deposits. Suppose an adversary deposits 10 bitcoins into an exchange and has his account credited.
What stops an adversary from mining a private chain with a transaction that conflicts with his previous deposit transaction. What would this mean for the exchange? Would the user have the ability to sell the Bitcoins credited to his account and defraud the exchange?