XSS (Cross-Site Scripting)
Cross-Site Scripting
An attack that executes malicious scripts in another user's browser
In Simple Terms
XSS is an attack that abuses input forms on websites to run unauthorized scripts in another user's browser. For example, an attacker might post malicious code in a comment section, causing it to run in the browser of anyone who views that page and steal their session information. The defining trait of this attack is that the malicious code appears to execute as a legitimate part of a trusted website.
Behind the Name
XSS stands for Cross-Site Scripting. The name traces back to the original attack technique: injecting scripts to steal data by "crossing" from one website to another — the "Cross-Site" part literally describes that boundary-hopping behavior.
Take a Closer Look!
XSS is an attack technique where, if a website has a security vulnerability, the attacker's malicious script is executed in the visitor's browser.
The harmful code runs as if it were a legitimate part of that website.
Simply put, it's a trap set by an attacker that activates when a user unknowingly triggers it.
A common method involves injecting code into search boxes or comment fields instead of ordinary text.
When a visitor's browser reads that code, they may be redirected to another site without warning, or have their session information — such as cookies — and other input data stolen.
Website developers need to sanitize user input to defend against this.
Without properly treating special characters as plain text, the browser may interpret them as executable instructions.
For users, the best defenses are avoiding suspicious links and keeping browsers up to date.