Mobile with mega pixel cameras, social networking sites, wireless sensor networks, earth-orbiting satellites, finance market etc continuously generating more and more data than ever before: 90% of world’s data has been produced in last two years. This huge amount of data is generated by different sources. Verification, authorization, authenticity, privacy such types of security issues is becoming major concern of big data in heterogeneous environments. To maintain the authenticity and preserve privacy of large amount of data is always an issue. In this paper authors discussed the data privacy and security issues such as node authentication, attribute linkage, degree attack distributed data, data loss etc. Authors also discussed some security techniques which help to maintain and preserve privacy and security of data. Main focus of this paper is to give an overview of the current issues in big data that can violate the individual’s privacy.