A vulnerability in the Umbrella Connector component of Cisco IOS XE Software for Cisco Catalyst 9200 Series Switches could allow an unauthenticated, remote attacker to trigger a reload, resulting in a denial of service condition on an affected device. The vulnerability is due to insufficient error handling when parsing DNS requests. An attacker could exploit this vulnerability by sending a series of malicious DNS requests to an Umbrella Connector client interface of an affected device. A successful exploit could allow the attacker to cause a crash of the iosd process, which triggers a reload of the affected device.

A vulnerability in the packet processing functionality of Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to inefficient memory management. An attacker could exploit this vulnerability by sending a high rate of IPv4 or IPv6 traffic through an affected device. This traffic would need to match a configured block action in an access control policy. An exploit could allow the attacker to cause a memory exhaustion condition on the affected device, which would result in a DoS for traffic transiting the device, as well as sluggish performance of the management interface. Once the flood is stopped, performance should return to previous states.

A vulnerability in the TCP/IP traffic handling function of the Snort Detection Engine of Cisco Firepower Threat Defense (FTD) Software and Cisco FirePOWER Services could allow an unauthenticated, remote attacker to cause legitimate network traffic to be dropped, resulting in a denial of service (DoS) condition. This vulnerability is due to the improper handling of TCP/IP network traffic. An attacker could exploit this vulnerability by sending a large amount of TCP/IP network traffic through the affected device. A successful exploit could allow the attacker to cause the Cisco FTD device to drop network traffic, resulting in a DoS condition. The affected device must be rebooted to resolve the DoS condition.

A vulnerability in system resource management in Cisco UCS 6400 and 6500 Series Fabric Interconnects that are in Intersight Managed Mode (IMM) could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on the Device Console UI of an affected device. This vulnerability is due to insufficient rate-limiting of TCP connections to an affected device. An attacker could exploit this vulnerability by sending a high number of TCP packets to the Device Console UI. A successful exploit could allow an attacker to cause the Device Console UI process to crash, resulting in a DoS condition. A manual reload of the fabric interconnect is needed to restore complete functionality.

A vulnerability in Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) 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 certain TLS connections that are processed by an affected device. An attacker could exploit this vulnerability by establishing a large number of concurrent TLS connections to an affected device. A successful exploit could allow the attacker to cause the device to drop new TLS email messages that come from the associated email servers. Exploitation of this vulnerability does not cause the affected device to unexpectedly reload. The device will recover autonomously within a few hours of when the attack is halted or mitigated.

A vulnerability in the processing of SSH connections of Cisco Firepower Management Center (FMC) and Cisco Firepower Threat Defense (FTD) 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 error handling when an SSH session fails to be established. An attacker could exploit this vulnerability by sending a high rate of crafted SSH connections to the instance. A successful exploit could allow the attacker to cause resource exhaustion, resulting in a reboot on the affected device.

A vulnerability in the Cisco Fabric Services over IP (CFSoIP) 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 insufficient validation of incoming CFSoIP packets. An attacker could exploit this vulnerability by sending crafted CFSoIP packets to an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition.

A vulnerability in the NETCONF over SSH feature of Cisco IOS XE Software could allow a low-privileged, authenticated, remote attacker to cause a denial of service condition (DoS) on an affected device. This vulnerability is due to insufficient resource management. An attacker could exploit this vulnerability by initiating a large number of NETCONF over SSH connections. A successful exploit could allow the attacker to exhaust resources, causing the device to reload and resulting in a DoS condition on an affected device.

A vulnerability in the DNS inspection handler of Cisco Adaptive Security Appliance (ASA) Software and Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service condition (DoS) on an affected device. This vulnerability is due to a lack of proper processing of incoming requests. An attacker could exploit this vulnerability by sending crafted DNS requests at a high rate to an affected device. A successful exploit could allow the attacker to cause the device to stop responding, resulting in a DoS condition.

A vulnerability in the Cisco Discovery Protocol functionality of Cisco ATA 190 Series Adaptive Telephone Adapter firmware could allow an unauthenticated, adjacent attacker to cause a DoS condition of an affected device. This vulnerability is due to missing length validation of certain Cisco Discovery Protocol packet header fields. An attacker could exploit this vulnerability by sending crafted Cisco Discovery Protocol packets to an affected device. A successful exploit could allow the attacker to cause the device to exhaust available memory and cause the service to restart. Cisco has released firmware updates that address this vulnerability.

A vulnerability in the SSH server of Cisco Adaptive Security Appliance (ASA) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition for the SSH server of an affected device. This vulnerability is due to a logic error when an SSH session is established. An attacker could exploit this vulnerability by sending crafted SSH messages to an affected device. A successful exploit could allow the attacker to exhaust available SSH resources on the affected device so that new SSH connections to the device are denied, resulting in a DoS condition. Existing SSH connections to the device would continue to function normally. The device must be rebooted manually to recover. However, user traffic would not be impacted and could be managed using a remote application such as Cisco Adaptive Security Device Manager (ASDM).

A vulnerability in the External Border Gateway Protocol (eBGP) implementation 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 eBGP traffic is mapped to a shared hardware rate-limiter queue. An attacker could exploit this vulnerability by sending large amounts of network traffic with certain characteristics through an affected device. A successful exploit could allow the attacker to cause eBGP neighbor sessions to be dropped, leading to a DoS condition in the network.

A vulnerability in the Internet Key Exchange Version 2 (IKEv2) implementation of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an authenticated, remote attacker to trigger a denial of service (DoS) condition on an affected device. This vulnerability is due to improper control of a resource. An attacker with the ability to spoof a trusted IKEv2 site-to-site VPN peer and in possession of valid IKEv2 credentials for that peer could exploit this vulnerability by sending malformed, authenticated IKEv2 messages to an affected device. A successful exploit could allow the attacker to trigger a reload of the device.

A vulnerability in SSL/TLS message handler for Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability exists because incoming SSL/TLS packets are not properly processed. An attacker could exploit this vulnerability by sending a crafted SSL/TLS packet to an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition.

Multiple vulnerabilities in the Distance Vector Multicast Routing Protocol (DVMRP) feature of Cisco IOS XR Software could allow an unauthenticated, remote attacker to either immediately crash the Internet Group Management Protocol (IGMP) process or make it consume available memory and eventually crash. The memory consumption may negatively impact other processes that are running on the device. These vulnerabilities are due to the incorrect handling of IGMP packets. An attacker could exploit these vulnerabilities by sending crafted IGMP traffic to an affected device. A successful exploit could allow the attacker to immediately crash the IGMP process or cause memory exhaustion, resulting in other processes becoming unstable. These processes may include, but are not limited to, interior and exterior routing protocols. Cisco will release software updates that address these vulnerabilities.

A vulnerability in the web-based management interface of Cisco SD-WAN vManage Software could allow an authenticated, remote attacker to consume excessive system memory and cause a denial of service (DoS) condition on an affected system. The vulnerability is due to inefficient memory management. An attacker could exploit this vulnerability by sending a large number of crafted HTTP requests to the affected web-based management interface. A successful exploit could allow the attacker to exhaust system memory, which could cause the system to stop processing new connections and could result in a DoS condition.

A vulnerability in Cisco Aironet Series Access Points Software could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to the improper processing of client packets that are sent to an affected access point (AP). An attacker could exploit this vulnerability by sending a large number of sustained client packets to the affected AP. A successful exploit could allow the attacker to cause the affected AP to crash, resulting in a DoS condition.

A vulnerability in the memory management of Cisco Adaptive Security Appliance (ASA) Software and Firepower Threat Defense (FTD) 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 resource management when connection rates are high. An attacker could exploit this vulnerability by opening a significant number of connections on an affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition.

A vulnerability in the Address Resolution Protocol (ARP) implementation of Cisco IOS XR Software could allow an unauthenticated, adjacent attacker to trigger a broadcast storm, leading to a denial of service (DoS) condition on an affected device.  This vulnerability is due to how Cisco IOS XR Software processes a high, sustained rate of ARP traffic hitting the management interface. Under certain conditions, an attacker could exploit this vulnerability by sending an excessive amount of traffic to the management interface of an affected device, overwhelming its ARP processing capabilities. A successful exploit could result in degraded device performance, loss of management connectivity, and complete unresponsiveness of the system, leading to a DoS condition.

A vulnerability in the Cisco Aironet Series Access Points (APs) software could allow an authenticated, adjacent attacker to cause an affected device to reload unexpectedly, resulting in a denial of service (DoS) condition. The vulnerability is due to a deadlock condition that may occur when an affected AP attempts to dequeue aggregated traffic that is destined to an attacker-controlled wireless client. An attacker who can successfully transition between multiple Service Set Identifiers (SSIDs) hosted on the same AP while replicating the required traffic patterns could trigger the deadlock condition. A watchdog timer that detects the condition will trigger a reload of the device, resulting in a DoS condition while the device restarts.

A vulnerability in the cryptographic hardware accelerator driver of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a temporary denial of service (DoS) condition. The vulnerability exists because the affected devices have a limited amount of Direct Memory Access (DMA) memory and the affected software improperly handles resources in low-memory conditions. An attacker could exploit this vulnerability by sending a sustained, high rate of malicious traffic to an affected device to exhaust memory on the device. A successful exploit could allow the attacker to exhaust DMA memory on the affected device, which could cause the device to reload and result in a temporary DoS condition.

A vulnerability in the DHCP snooping security feature of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a full interface queue wedge, which could result in a denial of service (DoS) condition. This vulnerability is due to improper handling of DHCP request packets. An attacker could exploit this vulnerability by sending DHCP request packets to an affected device. A successful exploit could allow the attacker to cause packets to wedge in the queue, creating a DoS condition for downstream devices of the affected system and requiring that the system restart to drain the queue. Note: This vulnerability can be exploited with either unicast or broadcast DHCP packets on a VLAN that does not have DHCP snooping enabled.

A vulnerability in the Virtual Shell (VSH) session management for Cisco NX-OS Software could allow an authenticated, remote attacker to cause a VSH process to fail to delete upon termination. This can lead to a build-up of VSH processes that overtime can deplete system memory. When there is no system memory available, this can cause unexpected system behaviors and crashes. The vulnerability is due to the VSH process not being properly deleted when a remote management connection to the device is disconnected. An attacker could exploit this vulnerability by repeatedly performing a remote management connection to the device and terminating the connection in an unexpected manner. A successful exploit could allow the attacker to cause the VSH processes to fail to delete, which can lead to a system-wide denial of service (DoS) condition. The attacker must have valid user credentials to log in to the device using the remote management connection.

A vulnerability in the Network Time Protocol (NTP) feature of Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to excessive use of system resources when the affected device is logging a drop action for received MODE_PRIVATE (Mode 7) NTP packets. An attacker could exploit this vulnerability by flooding the device with a steady stream of Mode 7 NTP packets. A successful exploit could allow the attacker to cause high CPU and memory usage on the affected device, which could cause internal system processes to restart or cause the affected device to unexpectedly reload. Note: The NTP feature is enabled by default.

A vulnerability in the cryptographic driver for Cisco Adaptive Security Appliance Software (ASA) and Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the device to reboot unexpectedly. The vulnerability is due to incomplete input validation of a Secure Sockets Layer (SSL) or Transport Layer Security (TLS) ingress packet header. An attacker could exploit this vulnerability by sending a crafted TLS/SSL packet to an interface on the targeted device. An exploit could allow the attacker to cause the device to reload, which will result in a denial of service (DoS) condition. Note: Only traffic directed to the affected system can be used to exploit this vulnerability. This vulnerability affects systems configured in routed and transparent firewall mode and in single or multiple context mode. This vulnerability can be triggered by IPv4 and IPv6 traffic. A valid SSL or TLS session is required to exploit this vulnerability.

A vulnerability in the interactions between the DHCP and TFTP features for Cisco Small Business 300 Series (Sx300) Managed Switches could allow an unauthenticated, remote attacker to cause the device to become low on system memory, which in turn could lead to an unexpected reload of the device and result in a denial of service (DoS) condition on an affected device. The vulnerability is due to a failure to free system memory when an unexpected DHCP request is received. An attacker could exploit this vulnerability by sending a crafted DHCP packet to the targeted device. A successful exploit could allow the attacker to cause an unexpected reload of the device.

A vulnerability in the processing of IP Service Level Agreement (SLA) packets by Cisco IOS Software and Cisco IOS XE software could allow an unauthenticated, remote attacker to cause an interface wedge and an eventual denial of service (DoS) condition on the affected device. The vulnerability is due to improper socket resources handling in the IP SLA responder application code. An attacker could exploit this vulnerability by sending crafted IP SLA packets to an affected device. An exploit could allow the attacker to cause an interface to become wedged, resulting in an eventual denial of service (DoS) condition on the affected device.

A vulnerability in the internal packet-processing functionality of Cisco Firepower Threat Defense (FTD) Software for the Cisco Firepower 2100 Series could allow an unauthenticated, remote attacker to cause an affected device to stop processing traffic, resulting in a denial of service (DoS) condition. The vulnerability is due to a logic error, which may prevent ingress buffers from being replenished under specific traffic conditions. An attacker could exploit this vulnerability by sending a series of crafted packets to an affected device. A successful exploit could allow the attacker to consume all input buffers, which are shared between all interfaces, leading to a queue wedge condition in all active interfaces. This situation would cause an affected device to stop processing any incoming traffic and result in a DoS condition until the device is reloaded manually.

A vulnerability in the UDP protocol implementation for Cisco IoT Field Network Director (IoT-FND) could allow an unauthenticated, remote attacker to exhaust system resources, resulting in a denial of service (DoS) condition. The vulnerability is due to improper resource management for UDP ingress packets. An attacker could exploit this vulnerability by sending a high rate of UDP packets to an affected system within a short period of time. A successful exploit could allow the attacker to exhaust available system resources, resulting in a DoS condition.

Multiple vulnerabilities in the Server Message Block (SMB) Protocol preprocessor detection engine for Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, adjacent or remote attacker to cause a denial of service (DoS) condition. For more information about these vulnerabilities, see the Details section of this advisory.

Multiple vulnerabilities in the Server Message Block (SMB) Protocol preprocessor detection engine for Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, adjacent or remote attacker to cause a denial of service (DoS) condition. For more information about these vulnerabilities, see the Details section of this advisory.

A vulnerability in the Internet Key Exchange version 1 (IKEv1) feature of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to trigger a reload of an affected device, resulting in a denial of service (DoS) condition. The vulnerability is due to improper management of system memory. An attacker could exploit this vulnerability by sending malicious IKEv1 traffic to an affected device. The attacker does not need valid credentials to authenticate the VPN session, nor does the attacker's source address need to match a peer statement in the crypto map applied to the ingress interface of the affected device. An exploit could allow the attacker to exhaust system memory resources, leading to a reload of an affected device.

A vulnerability in the Control and Provisioning of Wireless Access Points (CAPWAP) protocol implementation of Cisco Aironet and Catalyst 9100 Access Points (APs) could allow an unauthenticated, adjacent attacker to cause an affected device to restart unexpectedly, resulting in a denial of service (DoS) condition. The vulnerability is due to improper resource management during CAPWAP message processing. An attacker could exploit this vulnerability by sending a high volume of legitimate wireless management frames within a short time to an affected device. A successful exploit could allow the attacker to cause a device to restart unexpectedly, resulting in a DoS condition for clients associated with the AP.

A vulnerability in the implementation of Border Gateway Protocol (BGP) Ethernet VPN (EVPN) functionality in Cisco IOS XR Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. The vulnerability is due to incorrect processing of a BGP update message that contains crafted EVPN attributes. An attacker could indirectly exploit the vulnerability by sending BGP EVPN update messages with a specific, malformed attribute to an affected system and waiting for a user on the device to display the EVPN operational routes’ status. If successful, the attacker could cause the BGP process to restart unexpectedly, resulting in a DoS condition. The Cisco implementation of BGP accepts incoming BGP traffic only from explicitly defined peers. To exploit this vulnerability, the malicious BGP update message would need to come from a configured, valid BGP peer, or would need to be injected by the attacker into the victim's BGP network on an existing, valid TCP connection to a BGP peer.

Multiple vulnerabilities in the implementation of Border Gateway Protocol (BGP) Ethernet VPN (EVPN) functionality in Cisco IOS XR Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. The vulnerabilities are due to incorrect processing of BGP update messages that contain crafted EVPN attributes. An attacker could exploit these vulnerabilities by sending BGP EVPN update messages with malformed attributes to be processed by an affected system. A successful exploit could allow the attacker to cause the BGP process to restart unexpectedly, resulting in a DoS condition. The Cisco implementation of BGP accepts incoming BGP traffic only from explicitly defined peers. To exploit these vulnerabilities, the malicious BGP update message would need to come from a configured, valid BGP peer, or would need to be injected by the attacker into the victim's BGP network on an existing, valid TCP connection to a BGP peer.

Multiple vulnerabilities in the implementation of Border Gateway Protocol (BGP) Ethernet VPN (EVPN) functionality in Cisco IOS XR Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. The vulnerabilities are due to incorrect processing of BGP update messages that contain crafted EVPN attributes. An attacker could exploit these vulnerabilities by sending BGP EVPN update messages with malformed attributes to be processed by an affected system. A successful exploit could allow the attacker to cause the BGP process to restart unexpectedly, resulting in a DoS condition. The Cisco implementation of BGP accepts incoming BGP traffic only from explicitly defined peers. To exploit these vulnerabilities, the malicious BGP update message would need to come from a configured, valid BGP peer, or would need to be injected by the attacker into the victim's BGP network on an existing, valid TCP connection to a BGP peer.

A vulnerability in the web-based management interface of Cisco IC3000 Industrial Compute Gateway could allow an authenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability exists because the affected software improperly manages system resources. An attacker could exploit this vulnerability by opening a large number of simultaneous sessions on the web-based management interface of an affected device. A successful exploit could allow the attacker to cause a DoS condition of the web-based management interface, preventing normal management operations.

A vulnerability in the filesystem resource management code of Cisco IOS XE Software could allow an unauthenticated, remote attacker to exhaust filesystem resources on an affected device and cause a denial of service (DoS) condition. The vulnerability is due to ineffective management of the underlying filesystem resources. An attacker could exploit this vulnerability by performing specific actions that result in messages being sent to specific operating system log files. A successful exploit could allow the attacker to exhaust available filesystem space on an affected device. This could cause the device to crash and reload, resulting in a DoS condition for clients whose network traffic is transiting the device. Upon reload of the device, the impacted filesystem space is cleared, and the device will return to normal operation. However, continued exploitation of this vulnerability could cause subsequent forced crashes and reloads, which could lead to an extended DoS condition.

ClamAV versions prior to 0.101.3 are susceptible to a zip bomb vulnerability where an unauthenticated attacker can cause a denial of service condition by sending crafted messages to an affected system.

A vulnerability in the WebVPN feature of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause increased CPU utilization on an affected device. The vulnerability is due to excessive processing load for a specific WebVPN HTTP page request. An attacker could exploit this vulnerability by sending multiple WebVPN HTTP page load requests for a specific URL. A successful exploit could allow the attacker to increase CPU load on the device, resulting in a denial of service (DoS) condition, which could cause traffic to be delayed through the device.

A vulnerability in the HTTP server code of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause the HTTP server to crash. The vulnerability is due to a logical error in the logging mechanism. An attacker could exploit this vulnerability by generating a high amount of long-lived connections to the HTTP service on the device. A successful exploit could allow the attacker to cause the HTTP server to crash.

A vulnerability in the configuration of the Pluggable Authentication Module (PAM) used in Cisco Firepower Threat Defense (FTD) Software, Cisco Firepower Management Center (FMC) Software, and Cisco FXOS Software could allow an authenticated, remote attacker to cause a denial of service (DoS) condition. The vulnerability is due to improper resource management in the context of user session management. An attacker could exploit this vulnerability by connecting to an affected system and performing many simultaneous successful Secure Shell (SSH) logins. A successful exploit could allow the attacker to exhaust system resources and cause the device to reload, resulting in a DoS condition. To exploit this vulnerability, the attacker needs valid user credentials on the system.

A vulnerability in a feature that monitors RADIUS requests on Cisco Identity Services Engine (ISE) Software could allow an unauthenticated, remote attacker to negatively affect the performance of an affected device. This vulnerability is due to insufficient management of system resources. An attacker could exploit this vulnerability by taking actions that cause Cisco ISE Software to receive specific RADIUS traffic. A successful and sustained exploit of this vulnerability could allow the attacker to cause reduced performance of the affected device, resulting in significant delays to RADIUS authentications. There are workarounds that address this vulnerability.

A vulnerability in Cisco Smart Software Manager On-Prem (SSM On-Prem) could allow an authenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to incorrect handling of multiple simultaneous device registrations on Cisco SSM On-Prem. An attacker could exploit this vulnerability by sending multiple device registration requests to Cisco SSM On-Prem. A successful exploit could allow the attacker to cause a DoS condition on an affected device.

A vulnerability in the implementation of Multiprotocol Border Gateway Protocol (MP-BGP) for the Layer 2 VPN (L2VPN) Ethernet VPN (EVPN) address family in Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. The vulnerability is due to incorrect processing of Border Gateway Protocol (BGP) update messages that contain crafted EVPN attributes. An attacker could exploit this vulnerability by sending BGP update messages with specific, malformed attributes to an affected device. A successful exploit could allow the attacker to cause an affected device to crash, resulting in a DoS condition.