The Basel Committee on Banking Supervision (BCBS) has revealed in its latest report the complex risks banks face when engaging in transactions on permissionless blockchains. The report points out that such transactions not only pose risks of money laundering and terrorist financing but also involve issues related to operations and security, governance, legal matters, settlement finality, and compliance. BCBS emphasizes that the reliance on unknown third parties in blockchain technology makes it difficult for banks to conduct effective due diligence and oversight, while also facing risks from political uncertainties. New legislation could alter the behavior of validators, leading to operational instability in the blockchain.