Due to the increasing amount of Web sites offering features to contribute rich content and the frequent failure of Web developers to properly sanitize user input, cross-site-scripting prevails as the most significant security threat to Web applications. Using cross-site scripting techniques, a malicious user can hijack Web sessions, craft credible phishing sites and using the browser based exploits can have complete access to victim machine. Previous work towards protecting against cross-site scripting attacks suffers from various drawbacks, such as practical infeasibility of deployment due to the need for client-side modifications, inability to reliably detect all injected scripts, and complex, error-prone parameterization. In this paper, we introduce a server-side solution for detecting and preventing cross-site scripting attacks using reverse proxy that intercepts all HTML responses, and allow or deny the request based on filtering techniques using regular expressions and blacklisting techniques.