A vulnerability in the web UI framework of Cisco IOS XE Software could allow an authenticated, remote attacker to make unauthorized changes to the filesystem of the affected device. The vulnerability is due to improper input validation. An attacker could exploit this vulnerability by crafting a malicious file and uploading it to the device. An exploit could allow the attacker to gain elevated privileges on the affected device.
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190327-afu