pfSense: pfSense-SA-19_01.webgui: Multiple XSS vulnerabilities in the WebGUI

Cross-Site Scripting (XSS) vulnerabilities were found in several pages of the
pfSense software WebGUI on version 2.4.4-p2 and earlier.

* On system_advanced_admin.php, a reflected XSS was possible via the
"webguiproto" parameter.
* On interfaces_assign.php, a reflected XSS was possible via interface
parameters such as "wan".
* On firewall_rules.php, stored XSS was possible due to a lack of encoding in
firewall_check_for_advanced_options(), and a lack of validation on
firewall_rules_edit.php, in the "dscp", "tag", "tagged", "statetype",
"vlanprio", "vlanprioset", "dnpipe", and "defaultqueue" parameters.
* On firewall_shaper.php, a reflected XSS was possible via the "name" parameter.
* On services_igmpproxy.php, a stored XSS was possible due to a lack of encoding
of the "address" parameter and a lack of validation on the same parameter in
services_igmpproxy_edit.php
* On services_ntpd_gps.php, a stored XSS was possible via the "gpstype"
parameter.
* On diag_traceroute.php, a reflected XSS was possible via the "host" parameter.

Due to the lack of proper encoding on the affected parameters susceptible to
XSS, arbitrary JavaScript could be executed in the user's browser. The user's
session cookie or other information from the session may be compromised.