In Apache 2.0 or later, you can specify 'AddDefaultCharset' to avoid XSS issues. However some HTML documents of this test suite written in 'UTF-8' encoding without regard for the 'AddDefaultCharset' setting.
If you are annoied with it you may set the following to 'httpd.conf'.
<Directory "/var/www/html/cpki"> AddDefaultCharset UTF-8 </Directory>