A wireless sensor network (WSN) is a distributed sensor network of wireless devices that can gather and communicate information through wireless links. The gathered information will be sent to the base station or sink for further processing. The Sensor in WSN communicates wirelessly, so device location can be changed at any time and network settings should be flexible. WSN are spatially distributed autonomous sensors to monitor physical environmental conditions such as temperature, sound, pressure etc. It started to connect with internet of things (IoT) through internet which has also an ability to connect the sensor nodes. Now, huge amounts of data which are collected by WSNs are being accessed by IoT. The objective of this paper is to identify security challenges and various issues in wireless sensor networks which are integrated with IoT. The wireless sensor network currently must deal with the main issues that are security. For certain type of attacks like eavesdropping, jamming, and spoofing. Finally, to address security and privacy issues in IoT domain of WSN a light has been shed on a few obstacles and potential future research avenues by using Machine Learning algorithms.