Ethereum founder Vitalik Buterin said that security limitations are the main reason why cross-chain bridges have not been successful.
Buterin shared a Reddit post on his Twitter account yesterday in which he advocated a multi-chain future. Buterin expressed his skepticism about cross-chain bridges in this post, suggesting that bridged assets are more susceptible to security vulnerabilities.
Buterin said the main reason he disapproved of cross-chain is the security limitation of bridges. According to him, experiencing a 51% attack on a chain does not mean that all security mechanisms have failed. In his detailed statement, Buterin said that in the event of a possible 51% attack, the attacker would not be able to propose a block because such a block would violate the consensus rules and therefore would be rejected by the network. To put it succinctly, even if 99% of the hash power is for illegally taking another wallet’s ETH, the nodes follow the remaining 1% of the chain as it is the only set of blocks that follow the protocol rules.
However, the real problem arises when users connect assets from their local blockchain to a non-native blockchain. If the native blockchain suffers a 51% attack that reverts the bridge transaction, these assets can be left in a silo as soon as the same transaction is confirmed on the non-native (target) blockchain. This leaves the user with a contract that is no longer fully supported on the native blockchain. Buterin also added that this principle applies to any Ethereum second layer:
Buterin underlines that using interrelated dApps across different chains can cause a “contagion effect” where a 51% attack could endanger the entire ecosystem. Buterin said that he did not expect such a problem to arise immediately, adding that the more assets on the bridges, the more attention it will draw to attackers.