A vulnerability in the web-based management interface of Session Initiation Protocol (SIP) Software for Cisco IP Phone 8800 Series could allow an unauthenticated, remote attacker to bypass authorization, access critical services, and cause a denial of service (DoS) condition. The vulnerability exists because the software fails to sanitize URLs before it handles requests. An attacker could exploit this vulnerability by submitting a crafted URL. A successful exploit could allow the attacker to gain unauthorized access to critical services and cause a DoS condition. This vulnerability affects Cisco IP Phone 8800 Series products running a SIP Software release prior to 11.0(5) for Wireless IP Phone 8821 and 8821-EX; and 12.5(1)SR1 for the IP Conference Phone 8832 and the rest of the IP Phone 8800 Series. Cisco IP Conference Phone 8831 is not affected.