The X-XSS-Protection response header is one of the major features of most of the web browsers to stop cross-site scripting. It stops the pages from loading when they detect reflected cross-site scripting attacks. It is found that the X XSS Protection header is disabled in the application. This application is at risk due to its vulnerability to Cross-site Scripting attacks.The X-XSS-Protection header is designed to enable the cross-site scripting filter built into modern web browsers.
X-XSS-Protection: 0 # Disable XSS filtering
X-XSS-Protection: 1 # Enables filtering. If cross site scripting detected - the browser will sanitise
X-XSS-Protection: 1; mode=block # Under this mode, when cross site scripting detected - the browser wont render the page
X-XSS-Protection: 1; report=<reporting-uri> # Enables filtering, when detected - the browser will sanitise and report the violation
X-XSS-Protection: 1; mode=block
The major impact for this violation is cross-scripting attacks.
The only mitigation is to enable the X-XSS-Protection and set the value to 1.
PHP
header("X-XSS-Protection: 1; mode=block");
Apache (.htaccess)
<IfModule mod_headers.c>
Header set X-XSS-Protection "1; mode=block"
</IfModule>
Nginx
add_header "X-XSS-Protection" "1; mode=block";