Every application is vulnerable to an attack of some kind due to security issues. But the security issues of a blockchain platform are very different from those of a traditional application due to its security model. Most of the attacks that are performed on a centralized system are not applicable to a blockchain-based application. The decentralization model of a blockchain application makes it difficult to find vulnerabilities. Unlike traditional databases, blockchain data is created by achieving consensus among the network's nodes, so the only way to compromise the blockchain network is by finding vulnerabilities in the consensus mechanism.
There are a number of ways to prevent a network from reaching a valid consensus. However, attacks will not be successful on all the blockchain platforms. A resilient network such as Bitcoin will not be vulnerable...