The HTTP/2 protocol allows a denial of service (server resource consumption) because request cancellation can reset many streams quickly, as exploited in the wild in August through October 2023.

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.

A vulnerability in the Link Layer Discovery Protocol (LLDP) feature for Cisco Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) Mode could allow an unauthenticated, adjacent attacker to cause a memory leak, which could result in an unexpected reload of the device. This vulnerability is due to incorrect error checking when parsing ingress LLDP packets. An attacker could exploit this vulnerability by sending a steady stream of crafted LLDP packets to an affected device. A successful exploit could allow the attacker to cause a memory leak, which could result in a denial of service (DoS) condition when the device unexpectedly reloads. Note: This vulnerability cannot be exploited by transit traffic through the device. The crafted LLDP packet must be targeted to a directly connected interface, and the attacker must be in the same broadcast domain as the affected device (Layer 2 adjacent). In addition, the attack surface for this vulnerability can be reduced by disabling LLDP on interfaces where it is not required.

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 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 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 NX-API feature of Cisco NX-OS Software could allow an authenticated, remote attacker to execute arbitrary commands with root privileges. The vulnerability is due to insufficient input validation of user supplied data that is sent to the NX-API. An attacker could exploit this vulnerability by sending a crafted HTTP POST request to the NX-API of an affected device. A successful exploit could allow the attacker to execute arbitrary commands with root privileges on the underlying operating system. Note: The NX-API feature is disabled by default.

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 Unidirectional Link Detection (UDLD) feature of Cisco FXOS Software, Cisco IOS Software, Cisco IOS XE Software, Cisco IOS XR Software, and Cisco NX-OS Software could allow an unauthenticated, adjacent attacker to cause an affected device to reload. This vulnerability is due to improper input validation of the UDLD packets. An attacker could exploit this vulnerability by sending specifically crafted UDLD packets to an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a denial of service (DoS) condition. Note: The UDLD feature is disabled by default, and the conditions to exploit this vulnerability are strict. An attacker must have full control of a directly connected device. On Cisco IOS XR devices, the impact is limited to the reload of the UDLD process.

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 MPLS Operation, Administration, and Maintenance (OAM) 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 improper input validation when an affected device is processing an MPLS echo-request or echo-reply packet. An attacker could exploit this vulnerability by sending malicious MPLS echo-request or echo-reply packets to an interface that is enabled for MPLS forwarding on the affected device. A successful exploit could allow the attacker to cause the MPLS OAM process to crash and restart multiple times, causing the affected device to reload and resulting in a DoS condition.

A vulnerability in the VXLAN Operation, Administration, and Maintenance (OAM) feature of Cisco NX-OS Software, known as NGOAM, could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper handling of specific packets with a Transparent Interconnection of Lots of Links (TRILL) OAM EtherType. An attacker could exploit this vulnerability by sending crafted packets, including the TRILL OAM EtherType of 0x8902, to a device that is part of a VXLAN Ethernet VPN (EVPN) fabric. A successful exploit could allow the attacker to cause an affected device to experience high CPU usage and consume excessive system resources, which may result in overall control plane instability and cause the affected device to reload. Note: The NGOAM feature is disabled by default.

A vulnerability in the Multi-Pod or Multi-Site network configurations for Cisco Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) mode could allow an unauthenticated, remote attacker to unexpectedly restart the device, resulting in a denial of service (DoS) condition. This vulnerability exists because TCP traffic sent to a specific port on an affected device is not properly sanitized. An attacker could exploit this vulnerability by sending crafted TCP data to a specific port that is listening on a public-facing IP address for the Multi-Pod or Multi-Site configuration. A successful exploit could allow the attacker to cause the device to restart unexpectedly, resulting in a DoS condition.

A vulnerability in Cisco Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) mode could allow an authenticated, local attacker to elevate privileges on an affected device. This vulnerability is due to insufficient restrictions during the execution of a specific CLI command. An attacker with administrative privileges could exploit this vulnerability by performing a command injection attack on the vulnerable command. A successful exploit could allow the attacker to access the underlying operating system as root.

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 Cisco Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) Mode could allow an unauthenticated, remote attacker to cause a queue wedge on a leaf switch, which could result in critical control plane traffic to the device being dropped. This could result in one or more leaf switches being removed from the fabric. This vulnerability is due to mishandling of ingress TCP traffic to a specific port. An attacker could exploit this vulnerability by sending a stream of TCP packets to a specific port on a Switched Virtual Interface (SVI) configured on the device. A successful exploit could allow the attacker to cause a specific packet queue to queue network buffers but never process them, leading to an eventual queue wedge. This could cause control plane traffic to be dropped, resulting in a denial of service (DoS) condition where the leaf switches are unavailable. Note: This vulnerability requires a manual intervention to power-cycle the device to recover.

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 Unidirectional Link Detection (UDLD) feature of Cisco FXOS Software and Cisco NX-OS Software could allow an unauthenticated, adjacent attacker to execute arbitrary code with administrative privileges or 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 crafted Cisco UDLD protocol packets to a directly connected, affected device. A successful exploit could allow the attacker to execute arbitrary code with administrative privileges or cause the Cisco UDLD process to crash and restart multiple times, causing the affected device to reload and resulting in a DoS condition. Note: The UDLD feature is disabled by default, and the conditions to exploit this vulnerability are strict. The attacker needs full control of a directly connected device. That device must be connected over a port channel that has UDLD enabled. To trigger arbitrary code execution, both the UDLD-enabled port channel and specific system conditions must exist. In the absence of either the UDLD-enabled port channel or the system conditions, attempts to exploit this vulnerability will result in a DoS condition. It is possible, but highly unlikely, that an attacker could control the necessary conditions for exploitation. The CVSS score reflects this possibility. However, given the complexity of exploitation, Cisco has assigned a Medium Security Impact Rating (SIR) to this vulnerability.

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 implementation of an internal file management service for Cisco Nexus 3000 Series Switches and Cisco Nexus 9000 Series Switches in standalone NX-OS mode that are running Cisco NX-OS Software could allow an unauthenticated, remote attacker to create, delete, or overwrite arbitrary files with root privileges on the device. This vulnerability exists because TCP port 9075 is incorrectly configured to listen and respond to external connection requests. An attacker could exploit this vulnerability by sending crafted TCP packets to an IP address that is configured on a local interface on TCP port 9075. A successful exploit could allow the attacker to create, delete, or overwrite arbitrary files, including sensitive files that are related to the device configuration. For example, the attacker could add a user account without the device administrator knowing.