What Is a 51% Attack in the Context of PoS?

A 51% attack in a PoS system occurs when a single entity or coordinated group controls 51% or more of the total staked cryptocurrency. With this majority stake, the attacker can potentially dictate the canonical chain, censor transactions, or perform double-spend attacks by finalizing their own malicious blocks.

However, the cost of acquiring 51% of the staked assets and the risk of massive slashing makes this attack economically prohibitive.