With the increasing expansion of communication and digital technologies in the legal profession, clients' confidential information is increasingly exposed to cyber threats. Despite the fundamental importance of the principle of confidentiality in Iranian law, the existing legal system lacks a specific and comprehensive framework for determining lawyers' liability for cybersecurity breaches and disclosure of clients' information. This legal and regulatory vacuum has led to confusion in identifying lawyers' obligations, difficulty in proving fault, and insufficient protection of clients' rights in lawsuits related to cyber incidents, necessitating a comprehensive examination of this issue. The present study aims to identify the legal foundations of lawyer liability in cybersecurity breaches, analyze the instances and civil effects of such breaches, conduct a comparative study of the approaches of selected legal systems, and provide legal and legislative solutions for preventing this phenomenon and protecting clients' confidential information. This research has been conducted using a descriptive-analytical approach and library research method. The required data were collected through studying and examining laws, regulations, legal books, scientific articles, and judicial precedents in the Iranian legal system and the legal systems of the United States, the United Kingdom, and the European Union, and were then analyzed using content analysis method. The foundations of civil liability of lawyers in cybersecurity breaches are based on the theory of fault; however, proving fault and causation in cyber incidents faces serious challenges such as the anonymity of attackers, the technical complexity of attacks, and the lack of objective standards. Furthermore, the comparative study shows that advanced legal systems, through enacting specific laws, establishing binding security standards, providing for notification obligations, and creating specialized supervisory bodies, have taken more effective steps in protecting clients' information.