A vulnerability in the IPv6 packet processing engine of Cisco Small Business Smart and Managed Switches could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to insufficient validation of incoming IPv6 traffic. An attacker could exploit this vulnerability by sending a crafted IPv6 packet through an affected device. A successful exploit could allow the attacker to cause an unexpected reboot of the switch, leading to a DoS condition. This vulnerability is specific to IPv6 traffic. IPv4 traffic is not affected.

A vulnerability in session management for the web-based interface of Cisco Small Business Smart and Managed Switches could allow an unauthenticated, remote attacker to defeat authentication protections and gain unauthorized access to the management interface. The attacker could obtain the privileges of the highjacked session account, which could include administrator privileges on the device. The vulnerability is due to the use of weak entropy generation for session identifier values. An attacker could exploit this vulnerability to determine a current session identifier through brute force and reuse that session identifier to take over an ongoing session. In this way, an attacker could take actions within the management interface with privileges up to the level of the administrative user.

A vulnerability in the web UI of Cisco Small Business Switches could allow an unauthenticated, remote attacker to access sensitive device information. The vulnerability exists because the software lacks proper authentication controls to information accessible from the web UI. An attacker could exploit this vulnerability by sending a malicious HTTP request to the web UI of an affected device. A successful exploit could allow the attacker to access sensitive device information, which includes configuration files.

A vulnerability in the web-based management interface of Cisco Small Business Smart and Managed Switches could allow an unauthenticated, remote attacker to conduct a cross-site scripting (XSS) attack against a user of the interface. The vulnerability is due to insufficient validation of user-supplied input by the web-based management interface of the affected device. An attacker could exploit this vulnerability by persuading a user of the interface to click a malicious link and access a specific page. A successful exploit could allow the attacker to execute arbitrary script code in the context of the affected interface or access sensitive, browser-based information.

A vulnerability in the Simple Network Management Protocol (SNMP) input packet processor of Cisco Small Business Sx200, Sx300, Sx500, ESW2 Series Managed Switches and Small Business Sx250, Sx350, Sx550 Series Switches could allow an authenticated, remote attacker to cause the SNMP application of an affected device to cease processing traffic, resulting in the CPU utilization reaching one hundred percent. Manual intervention may be required before a device resumes normal operations. The vulnerability is due to improper validation of SNMP protocol data units (PDUs) in SNMP packets. An attacker could exploit this vulnerability by sending a malicious SNMP packet to an affected device. A successful exploit could allow the attacker to cause the device to cease forwarding traffic, which could result in a denial of service (DoS) condition. Cisco has released firmware updates that address this vulnerability.

A vulnerability in the Secure Shell (SSH) authentication process of Cisco Small Business Switches software could allow an attacker to bypass client-side certificate authentication and revert to password authentication. The vulnerability exists because OpenSSH mishandles the authentication process. An attacker could exploit this vulnerability by attempting to connect to the device via SSH. A successful exploit could allow the attacker to access the configuration as an administrative user if the default credentials are not changed. There are no workarounds available; however, if client-side certificate authentication is enabled, disable it and use strong password authentication. Client-side certificate authentication is disabled by default.

A vulnerability in the Cisco Small Business Switches software could allow an unauthenticated, remote attacker to bypass the user authentication mechanism of an affected device. The vulnerability exists because under specific circumstances, the affected software enables a privileged user account without notifying administrators of the system. An attacker could exploit this vulnerability by using this account to log in to an affected device and execute commands with full admin rights. Cisco has not released software updates that address this vulnerability. This advisory will be updated with fixed software information once fixed software becomes available. There is a workaround to address this vulnerability.