A vulnerability in certain access control mechanisms for the Secure Shell (SSH) server implementation for Cisco Wireless LAN Controller (WLC) Software could allow an unauthenticated, adjacent attacker to access a CLI instance on an affected device. The vulnerability is due to a lack of proper input- and validation-checking mechanisms for inbound SSH connections on an affected device. An attacker could exploit this vulnerability by attempting to establish an SSH connection to an affected controller. An exploit could allow the attacker to access an affected device's CLI to potentially cause further attacks. This vulnerability has been fixed in version 8.5(140.0).
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190417-wlc-ssh