What Is the Relationship between a Coin’s Difficulty and Its Vulnerability to a 51% Attack?

A coin's mining difficulty is a measure of how hard it is to find a valid block. Low difficulty means less computational power (hash rate) is needed to mine a block.

For a low-difficulty coin, an attacker needs less total hash power to acquire 51% of the network's total hash rate. This makes the attack cheaper and more feasible, as the attacker can rent or purchase the necessary hardware more easily.