A vulnerability in the IPv6 DHCP (DHCPv6) client module of Cisco Adaptive Security Appliance (ASA) Software, Cisco Firepower Threat Defense (FTD) Software, Cisco IOS Software, and Cisco IOS XE 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 DHCPv6 messages. An attacker could exploit this vulnerability by sending crafted DHCPv6 messages to an affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition. Note: To successfully exploit this vulnerability, the attacker would need to either control the DHCPv6 server or be in a man-in-the-middle position.

A vulnerability in the CLI of Cisco SD-WAN Software could allow an authenticated, local attacker to gain elevated privileges. This vulnerability is due to improper access controls on commands within the application CLI. An attacker could exploit this vulnerability by running a maliciously crafted command on the application CLI. A successful exploit could allow the attacker to execute arbitrary commands as the root user. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability. https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sd-wan-priv-E6e8tEdF

Multiple vulnerabilities in the Login Enhancements (Login Block) feature of Cisco IOS Software could allow an unauthenticated, remote attacker to trigger a reload of an affected system, resulting in a denial of service (DoS) condition. These vulnerabilities affect Cisco devices that are running Cisco IOS Software Release 15.4(2)T, 15.4(3)M, or 15.4(2)CG and later. Cisco Bug IDs: CSCuy32360, CSCuz60599.

Multiple vulnerabilities in the Login Enhancements (Login Block) feature of Cisco IOS Software could allow an unauthenticated, remote attacker to trigger a reload of an affected system, resulting in a denial of service (DoS) condition. These vulnerabilities affect Cisco devices that are running Cisco IOS Software Release 15.4(2)T, 15.4(3)M, or 15.4(2)CG and later. Cisco Bug IDs: CSCuy32360, CSCuz60599.

A vulnerability in the crypto engine of the Cisco Integrated Services Module for VPN (ISM-VPN) running Cisco IOS Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to insufficient handling of VPN traffic by the affected device. An attacker could exploit this vulnerability by sending crafted VPN traffic to an affected device. A successful exploit could allow the attacker to cause the affected device to hang or crash, resulting in a DoS condition. Cisco Bug IDs: CSCvd39267.

A vulnerability in the Border Gateway Protocol (BGP) over an Ethernet Virtual Private Network (EVPN) for Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause the device to reload, resulting in a denial of service (DoS) condition, or potentially corrupt the BGP routing table, which could result in network instability. The vulnerability exists due to changes in the implementation of the BGP MPLS-Based Ethernet VPN RFC (RFC 7432) draft between IOS XE software releases. When the BGP Inclusive Multicast Ethernet Tag Route or BGP EVPN MAC/IP Advertisement Route update packet is received, it could be possible that the IP address length field is miscalculated. An attacker could exploit this vulnerability by sending a crafted BGP packet to an affected device after the BGP session was established. An exploit could allow the attacker to cause the affected device to reload or corrupt the BGP routing table; either outcome would result in a DoS. The vulnerability may be triggered when the router receives a crafted BGP message from a peer on an existing BGP session. This vulnerability affects all releases of Cisco IOS XE Software prior to software release 16.3 that support BGP EVPN configurations. If the device is not configured for EVPN, it is not vulnerable. Cisco Bug IDs: CSCui67191, CSCvg52875.

The DHCP relay subsystem of Cisco IOS 12.2 through 15.6 and Cisco IOS XE Software contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code and gain full control of an affected system. The attacker could also cause an affected system to reload, resulting in a denial of service (DoS) condition. The vulnerability is due to a buffer overflow condition in the DHCP relay subsystem of the affected software. An attacker could exploit this vulnerability by sending a crafted DHCP Version 4 (DHCPv4) packet to an affected system. A successful exploit could allow the attacker to execute arbitrary code and gain full control of the affected system or cause the affected system to reload, resulting in a DoS condition. Cisco Bug IDs: CSCsm45390, CSCuw77959.

A vulnerability in the Internet Key Exchange Version 2 (IKEv2) module of Cisco IOS 15.0 through 15.6 and Cisco IOS XE 3.5 through 16.5 could allow an unauthenticated, remote attacker to cause high CPU utilization, traceback messages, or a reload of an affected device that leads to a denial of service (DoS) condition. The vulnerability is due to how an affected device processes certain IKEv2 packets. An attacker could exploit this vulnerability by sending specific IKEv2 packets to an affected device to be processed. A successful exploit could allow the attacker to cause high CPU utilization, traceback messages, or a reload of the affected device that leads to a DoS condition. This vulnerability affects Cisco devices that have the Internet Security Association and Key Management Protocol (ISAKMP) enabled. Although only IKEv2 packets can be used to trigger this vulnerability, devices that are running Cisco IOS Software or Cisco IOS XE Software are vulnerable when ISAKMP is enabled. A device does not need to be configured with any IKEv2-specific features to be vulnerable. Many features use IKEv2, including different types of VPNs such as the following: LAN-to-LAN VPN; Remote-access VPN, excluding SSL VPN; Dynamic Multipoint VPN (DMVPN); and FlexVPN. Cisco Bug IDs: CSCvc41277.

A vulnerability in the implementation of a protocol in Cisco Integrated Services Routers Generation 2 (ISR G2) Routers running Cisco IOS 15.0 through 15.6 could allow an unauthenticated, adjacent attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition. The vulnerability is due to a misclassification of Ethernet frames. An attacker could exploit this vulnerability by sending a crafted Ethernet frame to an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition. Cisco Bug IDs: CSCvc03809.

A vulnerability in the implementation of Network Address Translation (NAT) functionality in Cisco IOS 12.4 through 15.6 could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to the improper translation of H.323 messages that use the Registration, Admission, and Status (RAS) protocol and are sent to an affected device via IPv4 packets. An attacker could exploit this vulnerability by sending a crafted H.323 RAS packet through an affected device. A successful exploit could allow the attacker to cause the affected device to crash and reload, resulting in a DoS condition. This vulnerability affects Cisco devices that are configured to use an application layer gateway with NAT (NAT ALG) for H.323 RAS messages. By default, a NAT ALG is enabled for H.323 RAS messages. Cisco Bug IDs: CSCvc57217.

The L2TP module in Cisco IOS XE 3.10S(.2) and earlier on ASR 1000 routers allows remote authenticated users to cause a denial of service (ESP card reload) via a malformed L2TP packet, aka Bug ID CSCun09973.

Cisco IOS before 15.1(1)SY1 allows remote authenticated users to cause a denial of service (device reload) by establishing a VPN session and then sending malformed IKEv2 packets, aka Bug ID CSCub39268.

Cisco IOS before 15.1(1)SY on ASR 1000 devices, when Multicast Listener Discovery (MLD) tracking is enabled for IPv6, allows remote attackers to cause a denial of service (device reload) via crafted MLD packets, aka Bug ID CSCtz28544.

Cisco ASR 1000 devices with software before 3.8S, when BDI routing is enabled, allow remote attackers to cause a denial of service (device reload) via crafted (1) broadcast or (2) multicast ICMP packets with fragmentation, aka Bug ID CSCub55948.

Cisco IOS XE on ASR1000 devices, when PPPoE termination is enabled, allows remote attackers to cause a denial of service (device reload) via a malformed PPPoE packet, aka Bug ID CSCuo55180.

Multiple vulnerabilities in the CLI of Cisco SD-WAN Software could allow an authenticated, local attacker to gain elevated privileges. These vulnerabilities are due to improper access controls on commands within the application CLI. An attacker could exploit these vulnerabilities by running a malicious command on the application CLI. A successful exploit could allow the attacker to execute arbitrary commands as the root user.

A vulnerability in the Internet Key Exchange Version 2 (IKEv2) support for the AutoReconnect feature of Cisco IOS Software and Cisco IOS XE Software could allow an authenticated, remote attacker to exhaust the free IP addresses from the assigned local pool. This vulnerability occurs because the code does not release the allocated IP address under certain failure conditions. An attacker could exploit this vulnerability by trying to connect to the device with a non-AnyConnect client. A successful exploit could allow the attacker to exhaust the IP addresses from the assigned local pool, which prevents users from logging in and leads to a denial of service (DoS) condition.

A vulnerability in the application-hosting subsystem of Cisco IOS XE Software could allow an authenticated, local attacker to elevate privileges to root on an affected device. The attacker could execute IOS XE commands outside the application-hosting subsystem Docker container as well as on the underlying Linux operating system. These commands could be run as the root user. The vulnerability is due to a combination of two factors: (a) incomplete input validation of the user payload of CLI commands, and (b) improper role-based access control (RBAC) when commands are issued at the command line within the application-hosting subsystem. An attacker could exploit this vulnerability by using a CLI command with crafted user input. A successful exploit could allow the lower-privileged attacker to execute arbitrary CLI commands with root privileges. The attacker would need valid user credentials to exploit this vulnerability.

A vulnerability in the file system permissions of Cisco IOS XE Software could allow an authenticated, local attacker to obtain read and write access to critical configuration or system files. The vulnerability is due to insufficient file system permissions on an affected device. An attacker could exploit this vulnerability by connecting to an affected device's guest shell, and accessing or modifying restricted files. A successful exploit could allow the attacker to view or modify restricted information or configurations that are normally not accessible to system administrators.

A vulnerability in the IP Version 4 (IPv4) processing code of Cisco IOS XE Software running on Cisco Catalyst 3850 and Cisco Catalyst 3650 Series Switches could allow an unauthenticated, remote attacker to cause high CPU utilization, traceback messages, or a reload of an affected device that leads to a denial of service (DoS) condition. The vulnerability is due to incorrect processing of certain IPv4 packets. An attacker could exploit this vulnerability by sending specific IPv4 packets to an IPv4 address on an affected device. A successful exploit could allow the attacker to cause high CPU utilization, traceback messages, or a reload of the affected device that leads to a DoS condition. If the switch does not reboot when under attack, it would require manual intervention to reload the device. This vulnerability affects Cisco Catalyst 3850 and Cisco Catalyst 3650 Series Switches that are running Cisco IOS XE Software Release 16.1.1 or later, until the first fixed release, and are configured with an IPv4 address. Cisco Bug IDs: CSCvd80714.

A vulnerability in the logic that handles access control to one of the hardware components in Cisco's proprietary Secure Boot implementation could allow an authenticated, local attacker to write a modified firmware image to the component. This vulnerability affects multiple Cisco products that support hardware-based Secure Boot functionality. The vulnerability is due to an improper check on the area of code that manages on-premise updates to a Field Programmable Gate Array (FPGA) part of the Secure Boot hardware implementation. An attacker with elevated privileges and access to the underlying operating system that is running on the affected device could exploit this vulnerability by writing a modified firmware image to the FPGA. A successful exploit could either cause the device to become unusable (and require a hardware replacement) or allow tampering with the Secure Boot verification process, which under some circumstances may allow the attacker to install and boot a malicious software image. An attacker will need to fulfill all the following conditions to attempt to exploit this vulnerability: Have privileged administrative access to the device. Be able to access the underlying operating system running on the device; this can be achieved either by using a supported, documented mechanism or by exploiting another vulnerability that would provide an attacker with such access. Develop or have access to a platform-specific exploit. An attacker attempting to exploit this vulnerability across multiple affected platforms would need to research each one of those platforms and then develop a platform-specific exploit. Although the research process could be reused across different platforms, an exploit developed for a given hardware platform is unlikely to work on a different hardware platform.

A vulnerability in the Ident protocol handler of Cisco IOS and IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload. The vulnerability exists because the affected software incorrectly handles memory structures, leading to a NULL pointer dereference. An attacker could exploit this vulnerability by opening a TCP connection to specific ports and sending traffic over that connection. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a denial of service (DoS) condition.

A vulnerability in Unified Threat Defense (UTD) in Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload. The vulnerability is due to improper validation of IPv6 packets through the UTD feature. An attacker could exploit this vulnerability by sending IPv6 traffic through an affected device that is configured with UTD. A successful exploit could allow the attacker to cause the device to reload, resulting in a denial of service (DoS) condition.

A vulnerability in the common Session Initiation Protocol (SIP) library of Cisco IOS and IOS XE 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 insufficient sanity checks on an internal data structure. An attacker could exploit this vulnerability by sending a sequence of malicious SIP messages to an affected device. An exploit could allow the attacker to cause a NULL pointer dereference, resulting in a crash of the iosd process. This triggers a reload of the device.

A vulnerability in Cisco IOS XE SD-WAN Software could allow an unauthenticated, local attacker to gain unauthorized access to an affected device. The vulnerability is due to the existence of default credentials within the default configuration of an affected device. An attacker who has access to an affected device could log in with elevated privileges. A successful exploit could allow the attacker to take complete control of the device. This vulnerability affects Cisco devices that are running Cisco IOS XE SD-WAN Software releases 16.11 and earlier.

A vulnerability in the CLI of Cisco IOS XE SD-WAN Software could allow an authenticated, local attacker to inject arbitrary commands that are executed with root privileges. The vulnerability is due to insufficient input validation. An attacker could exploit this vulnerability by authenticating to the device and submitting crafted input to the CLI utility. The attacker must be authenticated to access the CLI utility. A successful exploit could allow the attacker to execute commands with root privileges.

A vulnerability in Cisco IOS XE Software could allow an authenticated, local attacker to escalate their privileges to a user with root-level privileges. The vulnerability is due to insufficient validation of user-supplied content. This vulnerability could allow an attacker to load malicious software onto an affected device.

A vulnerability in the Cisco IOS XE ROM Monitor (ROMMON) Software for Cisco 4000 Series Integrated Services Routers, Cisco ASR 920 Series Aggregation Services Routers, Cisco ASR 1000 Series Aggregation Services Routers, and Cisco cBR-8 Converged Broadband Routers could allow an unauthenticated, physical attacker to break the chain of trust and load a compromised software image on an affected device. The vulnerability is due to the presence of a debugging configuration option in the affected software. An attacker could exploit this vulnerability by connecting to an affected device through the console, forcing the device into ROMMON mode, and writing a malicious pattern using that specific option on the device. A successful exploit could allow the attacker to break the chain of trust and load a compromised software image on the affected device. A compromised software image is any software image that has not been digitally signed by Cisco.

A vulnerability in the ISDN subsystem of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, adjacent attacker to cause a reload of an affected device, resulting in a denial of service (DoS) condition. The vulnerability is due to insufficient input validation when the ISDN Q.931 messages are processed. An attacker could exploit this vulnerability by sending a malicious ISDN Q.931 message to an affected device. A successful exploit could allow the attacker to cause the process to crash, resulting in a reload of the affected device.

A vulnerability in the IP Address Resolution Protocol (ARP) feature of Cisco IOS XE Software for Cisco ASR 1000 Series Aggregation Services Routers with a 20-Gbps Embedded Services Processor (ESP) installed could allow an unauthenticated, adjacent attacker to cause an affected device to reload, resulting in a denial of service condition. The vulnerability is due to insufficient error handling when an affected device has reached platform limitations. An attacker could exploit this vulnerability by sending a malicious series of IP ARP messages to an affected device. A successful exploit could allow the attacker to exhaust system resources, which would eventually cause the affected device to reload.