Internet of Things (IoT)-enabled systems have become essential across various sectors, driving convenience and efficiency in today’s fast-paced technological landscape. However, the convergence of internet-connected smart devices with physical processes introduces significant security vulnerabilities, making these systems increasingly susceptible to cyberattacks. It is, therefore, crucial to evaluate the risks associated with cyberattacks. This study presents a methodology to quantify security events in IoT systems by analysing key factors, including vulnerabilities, exploitability, and the potential impacts of attacks. The primary contributions include the development of a novel threat severity model for quantifying IoT security threats and the establishment of a threat assessment framework specifically designed for IoT systems. Additionally, the research provides a quantified analysis of IoT security events to inform the development of effective threat mitigation strategies. The proposed security event quantification model serves as a foundation for advancing the core concepts explored in this study.