The swift growth of the Internet of Things (IoT) has resulted in the integration of IoT devices with cloud computing, creating IoT cloud systems. Although this merger provides improved data storage, real-time analytics, and scalability, it also brings about significant cybersecurity challenges. This paper investigates the specific security vulnerabilities present in IoT cloud systems, concentrating on issues related to device authentication, data integrity, privacy, and network security. Additionally, it analyzes how the limited resources of IoT devices intensify these vulnerabilities, making them more prone to attacks such as Distributed Denial of Service (DDoS), data breaches, and malware attacks. By reviewing existing security protocols and new technologies, this research emphasizes the necessity for stronger security frameworks to safeguard IoT cloud ecosystems. Suggested approaches, including encryption methods, sophisticated authentication strategies, and AI-driven threat detection, are evaluated for their efficacy in reducing risks and ensuring secure data transmission. This study offers a thorough overview of the cybersecurity environment in IoT cloud systems, with the goal of informing future research and policy-making in this vital field.