This article investigates the physical layer security (PLS) performance in an Energy Harvesting Underlay Cognitive Radio Network (EHUCRN). Firstly, the article examines the impact of parameters such as primary transmitter power, interference power threshold, and expected security level on EHUCRN's Secrecy Outage Probability (SOP). Then, based on the findings, the article evaluates the PLS performance of the system. The results indicate that increasing the primary transmitter power reduces the PLS performance while raising the interference power threshold improves PLS performance. Furthermore, increasing the expected security level decreases the PLS performance. Additionally, the percentage of time spent collecting energy increases within a small range, resulting in an increasing PLS performance up to a peak value. However, if this percentage continues to increase within a large range, the PLS gradually decreases. Moreover, the results demonstrate that the PLS performance in EHUCRN is low due to relatively high SOP values.