If a vulnerability in the software connected to the network to obtain the user's privilege, a remote attacker could gain the privilege to use the computer. In addition, in a user environment in which an operating system for a specific series is used a lot, if a problem occurs in the operating system, considerable damage can occur. In particular, If an error is a security vulnerability, it can be a very big problem. Various studies have been conducted to find and respond to vulnerabilities in such a situation. Among various security technologies, the fuzzing technology is one of the most effective technologies to find errors in software. In this paper, I designed and implemented a fuzzing agent that can detect buffer overflow vulnerabilities that can occur in various applications. Through this fuzzing agent, application developers will be able to realize a more secure computing environment in which they can discover and fix vulnerabilities in their own applications.