Security is a fundamental concern for blockchains, as they are designed to be tamper-resistant and trustworthy. Consensus mechanisms play a crucial role in protecting the network, but there are still risks and attack vectors to consider.
51% Attacks: If a single entity controls more than half of the network’s validating power, they can potentially rewrite history or double-spend coins. PoW and PoS blockchains are both vulnerable to this if decentralization is lost.
Sybil Attacks: Attackers create many fake identities to gain influence over the network. Permissionless blockchains use economic costs (like mining or staking) to make this expensive.
Smart Contract Bugs: Vulnerabilities in smart contract code can be exploited, leading to loss of funds or unintended behavior.
Consensus Failures: Bugs or flaws in the consensus algorithm can cause forks, downtime, or loss of trust.