Layer 2 network filtering capabilities such as IPv6 RA guard or ARP inspection can be bypassed using combinations of VLAN 0 headers and LLC/SNAP headers.

A vulnerability in the Link Layer Discovery Protocol (LLDP) feature of Cisco FXOS Software and Cisco NX-OS Software could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper handling of specific fields in an LLDP frame. An attacker could exploit this vulnerability by sending a crafted LLDP packet to an interface of an affected device and having an authenticated user retrieve LLDP statistics from the affected device through CLI show commands or Simple Network Management Protocol (SNMP) requests. A successful exploit could allow the attacker to cause the LLDP service to crash and stop running on the affected device. In certain situations, the LLDP crash may result in a reload of the affected device. Note: LLDP is a Layer 2 link protocol. To exploit this vulnerability, an attacker would need to be directly connected to an interface of an affected device, either physically or logically (for example, through a Layer 2 Tunnel configured to transport the LLDP protocol).

A vulnerability in the network-operator user role implementation for Cisco NX-OS System Software could allow an authenticated, local attacker to improperly delete valid user accounts. The network-operator role should not be able to delete other configured users on the device. The vulnerability is due to a lack of proper role-based access control (RBAC) checks for the actions that a user with the network-operator role is allowed to perform. An attacker could exploit this vulnerability by authenticating to the device with user credentials that give that user the network-operator role. Successful exploitation could allow the attacker to impact the integrity of the device by deleting configured user credentials. The attacker would need valid user credentials for the device. This vulnerability affects the following Cisco products running Cisco NX-OS System Software: Nexus 3000 Series Switches, Nexus 3600 Platform Switches, Nexus 9000 Series Switches in standalone NX-OS mode, Nexus 9500 R-Series Line Cards and Fabric Modules. Cisco Bug IDs: CSCvg21120.

A vulnerability in the network stack of Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability exists because the software improperly releases resources when it processes certain IPv6 packets that are destined to an affected device. An attacker could exploit this vulnerability by sending multiple crafted IPv6 packets to an affected device. A successful exploit could cause the network stack to run out of available buffers, impairing operations of control plane and management plane protocols and resulting in a DoS condition. Manual intervention would be required to restore normal operations on the affected device. For more information about the impact of this vulnerability, see the Details section of this advisory.

A vulnerability in the OSPF version 3 (OSPFv3) feature of Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to incomplete input validation of specific OSPFv3 packets. An attacker could exploit this vulnerability by sending a malicious OSPFv3 link-state advertisement (LSA) to an affected device. A successful exploit could allow the attacker to cause the OSPFv3 process to crash and restart multiple times, causing the affected device to reload and resulting in a DoS condition. Note: The OSPFv3 feature is disabled by default. To exploit this vulnerability, an attacker must be able to establish a full OSPFv3 neighbor state with an affected device. For more information about exploitation conditions, see the Details section of this advisory.

A vulnerability in the Cisco Discovery Protocol feature of Cisco FXOS Software and Cisco NX-OS Software could allow an unauthenticated, adjacent attacker to execute arbitrary code with root privileges or cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper input validation of specific values that are within a Cisco Discovery Protocol message. An attacker could exploit this vulnerability by sending a malicious Cisco Discovery Protocol packet to an affected device. A successful exploit could allow the attacker to execute arbitrary code with root privileges or cause the Cisco Discovery Protocol process to crash and restart multiple times, which would cause the affected device to reload, resulting in a DoS condition. Note: Cisco Discovery Protocol is a Layer 2 protocol. To exploit this vulnerability, an attacker must be in the same broadcast domain as the affected device (Layer 2 adjacent).

A vulnerability in the Python interpreter of Cisco NX-OS Software could allow an authenticated, low-privileged, local attacker to escape the Python sandbox and gain unauthorized access to the underlying operating system of the device. The vulnerability is due to insufficient validation of user-supplied input. An attacker could exploit this vulnerability by manipulating specific functions within the Python interpreter. A successful exploit could allow an attacker to escape the Python sandbox and execute arbitrary commands on the underlying operating system with the privileges of the authenticated user.  Note: An attacker must be authenticated with Python execution privileges to exploit these vulnerabilities. For more information regarding Python execution privileges, see product-specific documentation, such as the section of the Cisco Nexus 9000 Series NX-OS Programmability Guide.

A vulnerability in the Python interpreter of Cisco NX-OS Software could allow an authenticated, low-privileged, local attacker to escape the Python sandbox and gain unauthorized access to the underlying operating system of the device. The vulnerability is due to insufficient validation of user-supplied input. An attacker could exploit this vulnerability by manipulating specific functions within the Python interpreter. A successful exploit could allow an attacker to escape the Python sandbox and execute arbitrary commands on the underlying operating system with the privileges of the authenticated user.  Note: An attacker must be authenticated with Python execution privileges to exploit these vulnerabilities. For more information regarding Python execution privileges, see product-specific documentation, such as the section of the Cisco Nexus 9000 Series NX-OS Programmability Guide.

A vulnerability in the Python interpreter of Cisco NX-OS Software could allow an authenticated, low-privileged, local attacker to escape the Python sandbox and gain unauthorized access to the underlying operating system of the device. The vulnerability is due to insufficient validation of user-supplied input. An attacker could exploit this vulnerability by manipulating specific functions within the Python interpreter. A successful exploit could allow an attacker to escape the Python sandbox and execute arbitrary commands on the underlying operating system with the privileges of the authenticated user.  Note: An attacker must be authenticated with Python execution privileges to exploit these vulnerabilities. For more information regarding Python execution privileges, see product-specific documentation, such as the section of the Cisco Nexus 9000 Series NX-OS Programmability Guide.