source: https://www.securityfocus.com/bid/13783/info
 
BookReview is prone to multiple cross-site scripting vulnerabilities. These issues are due to a failure in the application to properly sanitize user-supplied input.
 
An attacker may leverage these issues to have arbitrary script code executed in the browser of an unsuspecting user. This may facilitate the theft of cookie-based authentication credentials as well as other attacks. 

http://www.example.com/add_contents.htm?isbn=083081423X%22%3E%3Cscript%3Ealert(document.cookie)%3C/script%3E