A vulnerability in the implementation of Intermediate System–to–Intermediate System (IS–IS) routing protocol functionality in Cisco IOS XR Software could allow an unauthenticated attacker who is in the same IS-IS area to cause a denial of service (DoS) condition. The vulnerability is due to incorrect processing of IS–IS link-state protocol data units (PDUs). An attacker could exploit this vulnerability by sending specific link-state PDUs to an affected system to be processed. A successful exploit could allow the attacker to cause incorrect calculations used in the weighted remote shared risk link groups (SRLG) or in the IGP Flexible Algorithm. It could also cause tracebacks to the logs or potentially cause the receiving device to crash the IS–IS process, resulting in a DoS condition.

A vulnerability in the access-control logic of the NETCONF over Secure Shell (SSH) of Cisco IOS XR Software may allow connections despite an access control list (ACL) that is configured to deny access to the NETCONF over SSH of an affected device. The vulnerability is due to a missing check in the NETCONF over SSH access control list (ACL). An attacker could exploit this vulnerability by connecting to an affected device using NETCONF over SSH. A successful exploit could allow the attacker to connect to the device on the NETCONF port. Valid credentials are required to access the device. This vulnerability does not affect connections to the default SSH process on the device.

A vulnerability in the implementation of the Intermediate System–to–Intermediate System (IS–IS) routing protocol functionality in Cisco IOS XR Software could allow an authenticated, remote attacker to cause a denial of service (DoS) condition in the IS–IS process. The vulnerability is due to improper handling of a Simple Network Management Protocol (SNMP) request for specific Object Identifiers (OIDs) by the IS–IS process. An attacker could exploit this vulnerability by sending a crafted SNMP request to the affected device. A successful exploit could allow the attacker to cause a DoS condition in the IS–IS process.

A vulnerability in the JSON-RPC API feature in Cisco Crosswork Network Services Orchestrator (NSO) and ConfD that is used by the web-based management interfaces of Cisco Optical Site Manager and Cisco RV340 Dual WAN Gigabit VPN Routers could allow an authenticated, remote attacker to modify the configuration of an affected application or device.  This vulnerability is due to improper authorization checks on the API. An attacker with privileges sufficient to access the affected application or device could exploit this vulnerability by sending malicious requests to the JSON-RPC API. A successful exploit could allow the attacker to make unauthorized modifications to the configuration of the affected application or device, including creating new user accounts or elevating their own privileges on an affected system.

A vulnerability in the CLI of Cisco IOS XR Software could allow an authenticated, local attacker to read any file in the file system of the underlying Linux operating system. The attacker must have valid credentials on the affected device. This vulnerability is due to incorrect validation of the arguments that are passed to a specific CLI command. An attacker could exploit this vulnerability by logging in to an affected device with low-privileged credentials and using the affected command. A successful exploit could allow the attacker access files in read-only mode on the Linux file system.

A vulnerability in the CLI of Cisco IOS XR Software could allow an authenticated, local attacker to obtain read/write file system access on the underlying operating system of an affected device. This vulnerability is due to insufficient validation of user arguments that are passed to specific CLI commands. An attacker with a low-privileged account could exploit this vulnerability by using crafted commands at the prompt. A successful exploit could allow the attacker to elevate privileges to root.

A vulnerability in the SSH Server process of Cisco IOS XR Software could allow an authenticated, remote attacker to overwrite and read arbitrary files on the local device. This vulnerability is due to insufficient input validation of arguments that are supplied by the user for a specific file transfer method. An attacker with lower-level privileges could exploit this vulnerability by specifying Secure Copy Protocol (SCP) parameters when authenticating to a device. A successful exploit could allow the attacker to elevate their privileges and retrieve and upload files on a device that they should not have access to. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability. This advisory is available at the following link:https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-scp-inject-QwZOCv2 This advisory is part of the September 2021 release of the Cisco IOS XR Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2021 Cisco IOS XR Software Security Advisory Bundled Publication.

A vulnerability in the IPv6 protocol handling of the management interfaces of Cisco IOS XR Software could allow an unauthenticated, adjacent attacker to cause an IPv6 flood on the management interface network of an affected device. The vulnerability exists because the software incorrectly forwards IPv6 packets that have an IPv6 node-local multicast group address destination and are received on the management interfaces. An attacker could exploit this vulnerability by connecting to the same network as the management interfaces and injecting IPv6 packets that have an IPv6 node-local multicast group address destination. A successful exploit could allow the attacker to cause an IPv6 flood on the corresponding network. Depending on the number of Cisco IOS XR Software nodes on that network segment, exploitation could cause excessive network traffic, resulting in network degradation or a denial of service (DoS) condition. Cisco has released software updates that address this vulnerability. There are workarounds that address this vulnerability. This advisory is available at the following link:https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-xripv6-spJem78K

A vulnerability in the egress packet processing function of Cisco IOS XR Software for Cisco ASR 9000 Series Aggregation Services Routers and Cisco Network Convergence System (NCS) 5000 Series Routers could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to improper resource allocation when an affected device processes network traffic in software switching mode. An attacker could exploit this vulnerability by sending specific streams of Layer 2 or Layer 3 protocol data units (PDUs) to an affected device. A successful exploit could cause the affected device to run out of buffer resources, which could make the device unable to process or forward traffic, resulting in a DoS condition. The device would need to be restarted to regain functionality. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability. This advisory is available at the following link:https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-xr-cp-dos-ej8VB9QY

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 has released software updates that address these vulnerabilities. There are no workarounds that address these vulnerabilities. There are multiple mitigations available to customers depending on their needs. This advisory is available at the following link:https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-dvmrp-memexh-dSmpdvfz

A vulnerability in the implementation of the Intermediate System-to-Intermediate System (IS-IS) routing protocol functionality in Cisco IOS XR Software could allow an authenticated, remote attacker to cause a denial of service (DoS) condition in the IS-IS process. The vulnerability is due to improper handling of a Simple Network Management Protocol (SNMP) request for specific Object Identifiers (OIDs) by the IS-IS process. An attacker could exploit this vulnerability by sending a crafted SNMP request to the affected device. A successful exploit could allow the attacker to cause a DoS condition in the IS-IS process. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability. This advisory is available at the following link: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20200122-ios-xr-dos