A Path Traversal vulnerability in the diagnostic shell for Cisco IOS and IOS XE Software could allow an authenticated, local attacker to use certain diagnostic shell commands that can overwrite system files. These system files may be sensitive and should not be able to be overwritten by a user of the diagnostic shell. The vulnerability is due to lack of proper input validation for certain diagnostic shell commands. An attacker could exploit this vulnerability by authenticating to the device, entering the diagnostic shell, and providing crafted user input to commands at the local diagnostic shell CLI. Successful exploitation could allow the attacker to overwrite system files that should be restricted. Cisco Bug IDs: CSCvg41950.
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180207-ios