Multiple vulnerabilities that affect Cisco Catalyst Digital Building Series Switches and Cisco Catalyst Micro Switches could allow an attacker to execute persistent code at boot time or to permanently prevent the device from booting, resulting in a permanent denial of service (DoS) condition. For more information about these vulnerabilities, see the Details section of this advisory.

A vulnerability in Cisco IOS ROM Monitor (ROMMON) Software for Cisco Catalyst 6800 Series Switches could allow an unauthenticated, local attacker to bypass Cisco Secure Boot validation checks and load a compromised software image on an affected device. The vulnerability is due to the presence of a hidden command in the affected software. An attacker could exploit this vulnerability by connecting to an affected device via the console, forcing the device into ROMMON mode, and writing a malicious pattern to a specific memory address on the device. A successful exploit could allow the attacker to bypass signature validation checks by Cisco Secure Boot technology and load a compromised software image on the affected device. A compromised software image is any software image that has not been digitally signed by Cisco.