I checked the version and found two issues which were: 

1.     Potential persistent cross-site scripting issue: The DNN Framework contains code to support sanitizing user input. A failure to detect certain input as malicious could allow a hacker to use a cross-site scripting attack to execute html/javascript. (severity :Low)

2.     Potential reflective xss issue: The DNN Framework contains code to support searching across a lucent based search.  Part of this code fails to sanitize against input and could allow a hacker to use a cross-site scripting attack to execute malicious html/javascript. (severity :Low)

both issues are telling to upgrade to version 7.2.2 as it is stable for all the issues. As i have recently upgraded my application from 5.2.1 to 7.1.2 with a lot of trouble, so is there any other way to eradicate these issues without upgrading it?

Also i need to know something related to cross-site scripting by example , that how it can allow a hacker to attack my application?

Thanks,

ITneer