A vulnerability in the Day One setup process of Cisco IOS XE Software for Catalyst 9800 Series Wireless Controllers for Cloud (9800-CL) could allow an unauthenticated, remote attacker to access the public-key infrastructure (PKI) server that is running on an affected device. This vulnerability is due to incomplete cleanup upon completion of the Day One setup process. An attacker could exploit this vulnerability by sending Simple Certificate Enrollment Protocol (SCEP) requests to an affected device. A successful exploit could allow the attacker to request a certificate from the virtual wireless controller and then use the acquired certificate to join an attacker-controlled device to the virtual wireless controller.