(computing) cross-site scripting; XSS

(Internet) a website

important, significant / grave, solemn

importance, significance, seriousness, gravity

security

security; safety / (finance) security

the above / the top (position or direction) / the surface of / superior in skill, age, level, etc.

in addition; furthermore / on top of (which)

(law enforcement) police bodyguard; police officers responsible for close protection

question, problem on homework etc. / a question; a matter (of time etc.) / a problem (something that needs to be dealt with); a trouble / an issue; a matter