Wireless sensor networks are of a large number of low cost resource constrained sensor nodes. Each node has to sense certain phenomena and forward its data towards a central node, which is also called the base station. The range of applications include basic data reading like temperature to a wide variety of applications including agriculture. A large amount of work has happened into the design and analysis of the sensor devices. These sensor can handle high level of data exchange without reduction in performance. The data to be exchanged are of vital importance and need to be handled with high level of confidentiality. Though there are security algorithms that offers mechanisms for data confidentiality there is a rising need for improvement for better level of security. The hackers can be from node level to process level. This paper outlines the different security issues in wireless sensor network and provides scope for improvement. {\textcopyright} 2012 IEEE.