XSS (Cross site Scripting) is a security vulnerability in website applications. Once those vulnerabilities are exploited by attackers that can cause serious issues such as user information leakage and malicious changes background data. This article focuses on the management systems based on the CMS (Content Management System) framework, Taking DEDECMS as an example to analyze, exploit and protect stored type XSS vulnerabilities. At the end of this article, the suggestions for protecting against stored type XSS vulnerabilities are proposed, such as inputting filtering and validation, using HTTP only cookies, requiring to input verification codes, updating systems and libraries regularly, etc. This can help improve the efficiency of detection and patching vulnerabilities, and promote the development of security technology.