A vulnerability in the web server of Cisco Umbrella could allow an unauthenticated, remote attacker to redirect a user to an undesired web page. The vulnerability is due to improper input validation of the URL parameters in an HTTP request that is sent to an affected device. An attacker could exploit this vulnerability by sending a crafted HTTP request that could cause the web application to redirect the request to a specified malicious URL. A successful exploit could allow the attacker to redirect a user to a malicious website.