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.

IP-in-IP protocol specifies IP Encapsulation within IP standard (RFC 2003, STD 1) that decapsulate and route IP-in-IP traffic is vulnerable to spoofing, access-control bypass and other unexpected behavior due to the lack of validation to verify network packets before decapsulation and routing.

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 access control list (ACL) programming for port channel subinterfaces of Cisco Nexus 3000 and 9000 Series Switches in standalone NX-OS mode could allow an unauthenticated, remote attacker to send traffic that should be blocked through an affected device. This vulnerability is due to incorrect hardware programming that occurs when configuration changes are made to port channel member ports. An attacker could exploit this vulnerability by attempting to send traffic through an affected device. A successful exploit could allow the attacker to access network resources that should be protected by an ACL that was applied on port channel subinterfaces.

A vulnerability in the Simple Network Management Protocol (SNMP) input packet processor of Cisco NX-OS Software could allow an authenticated, remote attacker to cause the SNMP application on an affected device to restart unexpectedly. 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 crafted SNMP packet to an affected device. A successful exploit could allow the attacker to cause the SNMP application to restart multiple times, leading to a system-level restart and a denial of service (DoS) condition. This vulnerability affects Nexus 2000 Series Switches, Nexus 3000 Series Switches, Nexus 3500 Platform Switches, Nexus 3600 Platform Switches, Nexus 5500 Platform Switches, Nexus 5600 Platform Switches, Nexus 6000 Series Switches, Nexus 7000 Series Switches, Nexus 7700 Series Switches, Nexus 9000 Series Switches in standalone NX-OS mode, Nexus 9500 R-Series Line Cards and Fabric Modules, UCS 6100 Series Fabric Interconnects, UCS 6200 Series Fabric Interconnects, UCS 6300 Series Fabric Interconnects. Cisco Bug IDs: CSCuw99630, CSCvg71290, CSCvj67977.

A vulnerability in the Cisco Discovery Protocol (formerly known as CDP) subsystem of devices running, or based on, Cisco NX-OS Software contain a vulnerability that could allow an unauthenticated, adjacent attacker to create a denial of service (DoS) condition. The vulnerability is due to a failure to properly validate certain fields within a Cisco Discovery Protocol message prior to processing it. An attacker with the ability to submit a Cisco Discovery Protocol message designed to trigger the issue could cause a DoS condition on an affected device while the device restarts. This vulnerability affects Firepower 4100 Series Next-Generation Firewall, Firepower 9300 Security Appliance, MDS 9000 Series Multilayer Director Switches, Nexus 1000V Series Switches, Nexus 1100 Series Cloud Services Platforms, Nexus 2000 Series Switches, Nexus 3000 Series Switches, Nexus 3500 Platform Switches, Nexus 3600 Platform Switches, Nexus 5500 Platform Switches, Nexus 5600 Platform Switches, Nexus 6000 Series Switches, Nexus 7000 Series Switches, Nexus 7700 Series Switches, Nexus 9000 Series Switches in NX-OS mode, Nexus 9500 R-Series Line Cards and Fabric Modules, UCS 6100 Series Fabric Interconnects, UCS 6200 Series Fabric Interconnects, UCS 6300 Series Fabric Interconnects. Cisco Bug IDs: CSCvc89242, CSCve40943, CSCve40953, CSCve40965, CSCve40970, CSCve40978, CSCve40992, CSCve41000, CSCve41007.

A vulnerability in the CLI of Cisco NX-OS Software could allow an authenticated, local attacker to execute arbitrary commands on the underlying operating system of an affected device. The vulnerability is due to insufficient validation of arguments passed to certain CLI commands. An attacker could exploit this vulnerability by including malicious input as the argument of an affected command. A successful exploit could allow the attacker to execute arbitrary commands on the underlying operating system with elevated privileges. An attacker would need valid administrator credentials to exploit this vulnerability. MDS 9000 Series Multilayer Switches are affected running software versions prior to 6.2(27) and 8.2(3). Nexus 3000 Series Switches are affected running software versions prior to 7.0(3)I4(9) and 7.0(3)I7(6). Nexus 3500 Platform Switches are affected running software versions prior to 6.0(2)A8(11) and 7.0(3)I7(6). Nexus 3600 Platform Switches are affected running software versions prior to 7.0(3)F3(5). Nexus 9000 Series Switches in Standalone NX-OS Mode are affected running software versions prior to 7.0(3)I4(9), 7.0(3)I7(6). Nexus 9500 R-Series Line Cards and Fabric Modules are affected running software versions prior to 7.0(3)F3(5). Nexus 7000 and 7700 Series Switches are affected running software versions prior to 6.2(22) and 8.2(3).

A vulnerability in the management interface of Cisco Application Policy Infrastructure Controller (APIC) software could allow an unauthenticated, adjacent attacker to gain unauthorized access on an affected device. The vulnerability is due to a lack of proper access control mechanisms for IPv6 link-local connectivity imposed on the management interface of an affected device. An attacker on the same physical network could exploit this vulnerability by attempting to connect to the IPv6 link-local address on the affected device. A successful exploit could allow the attacker to bypass default access control restrictions on an affected device. Cisco Application Policy Infrastructure Controller (APIC) devices running versions prior to 4.2(0.21c) are affected.

A vulnerability in Cisco Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) mode could allow an authenticated, remote attacker to access sensitive information. The vulnerability occurs because the affected software does not properly validate user-supplied input. An attacker could exploit this vulnerability by issuing certain commands with filtered query results on the device. This action may cause returned messages to display confidential system information. A successful exploit could allow the attacker to read sensitive information on the device.

A vulnerability in the Trusted Platform Module (TPM) functionality of software for Cisco Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) mode could allow an unauthenticated, local attacker with physical access to view sensitive information on an affected device. The vulnerability is due to a lack of proper data-protection mechanisms for disk encryption keys that are used within the partitions on an affected device hard drive. An attacker could exploit this vulnerability by obtaining physical access to the affected device to view certain cleartext keys. A successful exploit could allow the attacker to execute a custom boot process or conduct further attacks on an affected device.

A vulnerability in the SSH CLI key management functionality of Cisco NX-OS Software could allow an authenticated, local attacker to expose a user's private SSH key to all authenticated users on the targeted device. The attacker must authenticate with valid administrator device credentials. The vulnerability is due to incomplete error handling if a specific error type occurs during the SSH key export. An attacker could exploit this vulnerability by authenticating to the device and entering a crafted command at the CLI. A successful exploit could allow the attacker to expose a user's private SSH key. In addition, a similar type of error in the SSH key import could cause the passphrase-protected private SSH key to be imported unintentionally.

A vulnerability in the implementation of a CLI diagnostic command in Cisco FXOS Software and Cisco NX-OS Software could allow an authenticated, local attacker to view sensitive system files that should be restricted. The attacker could use this information to conduct additional reconnaissance attacks. The vulnerability is due to incomplete role-based access control (RBAC) verification. An attacker could exploit this vulnerability by authenticating to the device and issuing a specific CLI diagnostic command with crafted user-input parameters. An exploit could allow the attacker to perform an arbitrary read of a file on the device, and the file may contain sensitive information. The attacker needs valid device credentials to exploit this vulnerability.

A vulnerability in the Image Signature Verification feature of Cisco NX-OS Software could allow an authenticated, local attacker with administrator-level credentials to install a malicious software image on an affected device. The vulnerability is due to improper verification of digital signatures for software images. An attacker could exploit this vulnerability by loading an unsigned software image on an affected device. A successful exploit could allow the attacker to boot a malicious software image. Note: The fix for this vulnerability requires a BIOS upgrade as part of the software upgrade. For additional information, see the Details section of this advisory. Nexus 3000 Series Switches are affected running software versions prior to 7.0(3)I7(5). Nexus 9000 Series Fabric Switches in ACI Mode are affected running software versions prior to 13.2(1l). Nexus 9000 Series Switches in Standalone NX-OS Mode are affected running software versions prior to 7.0(3)I7(5). Nexus 9500 R-Series Line Cards and Fabric Modules are affected running software versions prior to 7.0(3)F3(5).

A vulnerability in the implementation of the Simple Network Management Protocol (SNMP) Access Control List (ACL) feature of Cisco NX-OS Software could allow an unauthenticated, remote attacker to perform SNMP polling of an affected device, even if it is configured to deny SNMP traffic. The vulnerability is due to an incorrect length check when the configured ACL name is the maximum length, which is 32 ASCII characters. An attacker could exploit this vulnerability by performing SNMP polling of an affected device. A successful exploit could allow the attacker to perform SNMP polling that should have been denied. The attacker has no control of the configuration of the SNMP ACL name.

A vulnerability in ICMP Version 6 (ICMPv6) processing in Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause a slow system memory leak, which over time could lead to a denial of service (DoS) condition. This vulnerability is due to improper error handling when an IPv6-configured interface receives a specific type of ICMPv6 packet. An attacker could exploit this vulnerability by sending a sustained rate of crafted ICMPv6 packets to a local IPv6 address on a targeted device. A successful exploit could allow the attacker to cause a system memory leak in the ICMPv6 process on the device. As a result, the ICMPv6 process could run out of system memory and stop processing traffic. The device could then drop all ICMPv6 packets, causing traffic instability on the device. Restoring device functionality would require a device reboot.

A vulnerability in the Link Layer Discovery Protocol (LLDP) for Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) mode could allow an unauthenticated, adjacent attacker to disable switching on a small form-factor pluggable (SFP) interface. This vulnerability is due to incomplete validation of the source of a received LLDP packet. An attacker could exploit this vulnerability by sending a crafted LLDP packet on an SFP interface to an affected device. A successful exploit could allow the attacker to disable switching on the SFP interface, which could disrupt network traffic.

A vulnerability in the Protocol Independent Multicast (PIM) feature of 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 insufficient input validation. An attacker could exploit this vulnerability by sending a crafted PIM packet to an affected device. A successful exploit could allow the attacker to cause a traffic loop, resulting in a DoS condition.

A vulnerability in the fabric infrastructure file system access control of Cisco Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) mode could allow an authenticated, local attacker to read arbitrary files on an affected system. This vulnerability is due to improper access control. An attacker with Administrator privileges could exploit this vulnerability by executing a specific vulnerable command on an affected device. A successful exploit could allow the attacker to read arbitrary files on the file system of the affected device.

A vulnerability in the implementation of the system login block-for command for Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause a login process to unexpectedly restart, causing a denial of service (DoS) condition. This vulnerability is due to a logic error in the implementation of the system login block-for command when an attack is detected and acted upon. An attacker could exploit this vulnerability by performing a brute-force login attack on an affected device. A successful exploit could allow the attacker to cause a login process to reload, which could result in a delay during authentication to the affected device.

A vulnerability in the Cisco Discovery Protocol service of Cisco FXOS Software and Cisco NX-OS Software could allow an unauthenticated, adjacent attacker to cause the service to restart, resulting in a denial of service (DoS) condition. This vulnerability is due to improper handling of Cisco Discovery Protocol messages that are processed by the Cisco Discovery Protocol service. An attacker could exploit this vulnerability by sending a series of malicious Cisco Discovery Protocol messages to an affected device. A successful exploit could allow the attacker to cause the Cisco Discovery Protocol service to fail and restart. In rare conditions, repeated failures of the process could occur, which could cause the entire device to restart.

A vulnerability in the SFTP server implementation for Cisco Nexus 3000 Series Switches and 9000 Series Switches in standalone NX-OS mode could allow an authenticated, remote attacker to download or overwrite files from the underlying operating system of an affected device. This vulnerability is due to a logic error when verifying the user role when an SFTP connection is opened to an affected device. An attacker could exploit this vulnerability by connecting and authenticating via SFTP as a valid, non-administrator user. A successful exploit could allow the attacker to read or overwrite files from the underlying operating system with the privileges of the authenticated user. There are workarounds that address this vulnerability.

Cisco NX-OS 6.1(2)I3(4) and 7.0(3)I1(1) on Nexus 9000 (N9K) devices allows remote attackers to cause a denial of service (CPU consumption or control-plane instability) or trigger unintended traffic forwarding via a Layer 2 packet with a reserved VLAN number, aka Bug ID CSCuw13560.

The CLI parser in Cisco NX-OS 4.1(2)E1(1), 6.2(11b), 6.2(12), 7.2(0)ZZ(99.1), 7.2(0)ZZ(99.3), and 9.1(1)SV1(3.1.8) on Nexus devices allows local users to execute arbitrary OS commands via crafted characters in a filename, aka Bug IDs CSCuv08491, CSCuv08443, CSCuv08480, CSCuv08448, CSCuu99291, CSCuv08434, and CSCuv08436.

Cisco NX-OS 6.2(10) on Nexus and MDS 9000 devices allows local users to execute arbitrary OS commands by entering crafted tar parameters in the CLI, aka Bug ID CSCus44856.

Buffer overflow in Cisco NX-OS on Nexus 1000V devices for VMware vSphere 7.3(0)ZN(0.81), Nexus 3000 devices 7.3(0)ZN(0.81), Nexus 4000 devices 4.1(2)E1(1c), Nexus 7000 devices 7.2(0)N1(0.1), and Nexus 9000 devices 7.3(0)ZN(0.81) allows remote attackers to cause a denial of service (IGMP process restart) via a malformed IGMPv3 packet that is mishandled during memory allocation, aka Bug IDs CSCuv69713, CSCuv69717, CSCuv69723, CSCuv69732, and CSCuv48908.

Buffer overflow in Cisco NX-OS on Nexus 1000V devices for VMware vSphere 7.3(0)ZN(0.9); Nexus 3000 devices 6.0(2)U5(1.41), 7.0(3)I2(0.373), and 7.3(0)ZN(0.83); Nexus 4000 devices 4.1(2)E1(1b); Nexus 7000 devices 6.2(14)S1; Nexus 9000 devices 7.3(0)ZN(0.9); and MDS 9000 devices 6.2 (13) and 7.1(0)ZN(91.99) and MDS SAN-OS 7.1(0)ZN(91.99) allows remote attackers to cause a denial of service (device outage) via a crafted ARP packet, related to incorrect MTU validation, aka Bug IDs CSCuv71933, CSCuv61341, CSCuv61321, CSCuu78074, CSCut37060, CSCuv61266, CSCuv61351, CSCuv61358, and CSCuv61366.

The global-configuration implementation on Cisco ASR 9000 devices with software 5.1.3 and 5.3.0 improperly closes vty sessions after a commit/end operation, which allows local users to cause a denial of service (tmp/config file creation, memory consumption, and device hang) via unspecified vectors, aka Bug ID CSCut93842.

Cisco NX-OS on Nexus 9000 devices 11.1(1c) allows remote authenticated users to cause a denial of service (device hang) via large files that are copied to a device's filesystem, aka Bug ID CSCuu77225.

Cisco Application Policy Infrastructure Controller (APIC) 1.0(1.110a) and 1.0(1e) on Nexus 9000 devices does not properly implement RBAC health scoring, which allows remote authenticated users to obtain sensitive information via unspecified vectors, aka Bug ID CSCuq77485.

Cisco NX-OS 1.1(1g) on Nexus 9000 devices allows remote authenticated users to discover cleartext passwords by leveraging the existence of a decryption mechanism, aka Bug ID CSCuu84391.