A vulnerability in the Guest Shell of Cisco IOS XE Software could allow an authenticated, local attacker to perform directory traversal on the base Linux operating system of Cisco IOS XE Software. The vulnerability is due to incomplete validation of certain commands. An attacker could exploit this vulnerability by first accessing the Guest Shell and then entering specific commands. A successful exploit could allow the attacker to execute arbitrary code on the base Linux operating system.
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190925-dt