A vulnerability in the DHCP version 4 (DHCPv4) server feature of Cisco IOS XR Software could allow an unauthenticated, remote attacker to trigger a crash of the dhcpd process, resulting in a denial of service (DoS) condition. This vulnerability exists because certain DHCPv4 messages are improperly validated when they are processed by an affected device. An attacker could exploit this vulnerability by sending a malformed DHCPv4 message to an affected device. A successful exploit could allow the attacker to cause a NULL pointer dereference, resulting in a crash of the dhcpd process. While the dhcpd process is restarting, which may take up to approximately two minutes, DHCPv4 server services are unavailable on the affected device. This could temporarily prevent network access to clients that join the network during that time period. Note: Only the dhcpd process crashes and eventually restarts automatically. The router does not reload.

The do_change_cipher_spec function in OpenSSL 0.9.6c to 0.9.6k, and 0.9.7a to 0.9.7c, allows remote attackers to cause a denial of service (crash) via a crafted SSL/TLS handshake that triggers a null dereference.

Multiple vulnerabilities in Cisco SD-WAN products could allow an unauthenticated, remote attacker to execute denial of service (DoS) attacks against an affected device. For more information about these vulnerabilities, see the Details section of this advisory.

A vulnerability in the EGG archive parsing module in Clam AntiVirus (ClamAV) Software versions 0.102.0 - 0.102.3 could allow an unauthenticated, remote attacker to cause a denial of service condition on an affected device. The vulnerability is due to a null pointer dereference. An attacker could exploit this vulnerability by sending a crafted EGG file to an affected device. An exploit could allow the attacker to cause the ClamAV scanning process crash, resulting in a denial of service condition.

A vulnerability in the Cisco Fabric Services component of Cisco FXOS Software and Cisco NX-OS Software could allow an unauthenticated attacker to cause process crashes, which could result in a denial of service (DoS) condition on an affected device. The attack vector is configuration dependent and could be remote or adjacent. For more information about the attack vector, see the Details section of this advisory. The vulnerability is due to insufficient error handling when the affected software parses Cisco Fabric Services messages. An attacker could exploit this vulnerability by sending malicious Cisco Fabric Services messages to an affected device. A successful exploit could allow the attacker to cause a reload of an affected device, which could result in a DoS condition.

Cisco Unified Personal Communicator 7.0 (1.13056) does not free allocated memory for received data and does not perform validation if memory allocation is successful, causing a remote denial of service condition.

A vulnerability in the RESTCONF and NETCONF-YANG access control list (ACL) function of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause the device to reload. The vulnerability is due to incorrect processing of the ACL that is tied to the RESTCONF or NETCONF-YANG feature. An attacker could exploit this vulnerability by accessing the device using RESTCONF or NETCONF-YANG. A successful exploit could allow an attacker to cause the device to reload, resulting in a denial of service (DoS) condition.

A vulnerability in the Internet Key Exchange version 2 (IKEv2) protocol for VPN termination of 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 is due to insufficient input validation. An attacker could exploit this vulnerability by sending crafted IKEv2 traffic to 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 TLS processing feature of Cisco Firepower Threat Defense (FTD) Software for Cisco Firepower 2100 Series could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to an issue that occurs when TLS traffic is processed. An attacker could exploit this vulnerability by sending certain TLS traffic over IPv4 through an affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition and impacting traffic to and through the affected device.

A vulnerability in the HTTP Server feature of Cisco IOS XE Software when the Telephony Service feature is enabled could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to a null pointer dereference when accessing specific URLs. An attacker could exploit this vulnerability by sending crafted HTTP traffic to an affected device. A successful exploit could allow the attacker to cause the affected device to reload, causing a DoS condition on the affected device.

A vulnerability in the DHCPv6 relay agent 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 handling of specific fields in a DHCPv6 RELAY-REPLY message. An attacker could exploit this vulnerability by sending a crafted DHCPv6 packet to any IPv6 address that is configured on an affected device. A successful exploit could allow the attacker to cause the dhcp_snoop process to crash and restart multiple times, causing the affected device to reload and resulting in a DoS condition.

A vulnerability in the web server of Cisco Integrated Management Controller (IMC) could allow an unauthenticated, remote attacker to cause the web server process to crash, causing a denial of service (DoS) condition on an affected system. The vulnerability is due to insufficient validation of user-supplied input on the web interface. An attacker could exploit this vulnerability by submitting a crafted HTTP request to certain endpoints of the affected software. A successful exploit could allow an attacker to cause the web server to crash. Physical access to the device may be required for a restart.

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 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 the Control and Provisioning of Wireless Access Points (CAPWAP) protocol processing of Cisco IOS XE Wireless Controller Software for the Catalyst 9000 Family could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to inadequate input validation of incoming CAPWAP packets encapsulating multicast DNS (mDNS) queries. An attacker could exploit this vulnerability by connecting to a wireless network and sending a crafted mDNS query, which would flow through and be processed by the wireless controller. A successful exploit could allow the attacker to cause the affected device to crash and reload, resulting in a DoS condition.

A vulnerability in the web services interface of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a buffer overflow on an affected system.  This vulnerability is due to insufficient boundary checks for specific data that is provided to the web services interface of an affected system. An attacker could exploit this vulnerability by sending a crafted HTTP request to the affected system. A successful exploit could allow the attacker to cause a buffer overflow condition on the affected system, which could cause the system to reload, resulting in a denial of service (DoS) condition.

A vulnerability in the IP Service Level Agreement (SLA) responder feature of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause the IP SLA responder to reuse an existing port, resulting in a denial of service (DoS) condition. The vulnerability exists because the IP SLA responder could consume a port that could be used by another feature. An attacker could exploit this vulnerability by sending specific IP SLA control packets to the IP SLA responder on an affected device. The control packets must include the port number that could be used by another configured feature. A successful exploit could allow the attacker to cause an in-use port to be consumed by the IP SLA responder, impacting the feature that was using the port and resulting in a DoS condition.

A vulnerability in the IKEv2 feature of Cisco IOS Software, IOS XE Software, Secure Firewall ASA Software, and Secure FTD Software could allow an unauthenticated, remote attacker to cause the device to reload, resulting in a DoS condition. This vulnerability is due to the improper processing of IKEv2 packets. An attacker could exploit this vulnerability by sending crafted IKEv2 packets to an affected device. A successful exploit could allow the attacker to cause an infinite loop that exhausts resources and could cause the device to reload.

A vulnerability in the web UI of Cisco Desk Phone 9800 Series, Cisco IP Phone 7800 and 8800 Series, and Cisco Video Phone 8875 running Cisco SIP Software could allow an unauthenticated, remote attacker to cause a DoS condition on an affected device. This vulnerability is due to a buffer overflow when an affected device processes HTTP packets. An attacker could exploit this vulnerability by sending crafted HTTP input to the device. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition. Note: To exploit this vulnerability, the phone must be registered to Cisco Unified Communications Manager and have Web Access enabled. Web Access is disabled by default.

A vulnerability in chat messaging features of Cisco Enterprise Chat and Email (ECE) could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. This vulnerability is due to improper validation of user-supplied input to chat entry points. An attacker could exploit this vulnerability by sending malicious requests to a messaging chat entry point in the affected application. A successful exploit could allow the attacker to cause the application to stop responding, resulting in a DoS condition. The application may not recover on its own and may need an administrator to manually restart services to recover.

A vulnerability in the Object Linking and Embedding 2 (OLE2) decryption routine of ClamAV could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to an integer underflow in a bounds check that allows for a heap buffer overflow read. An attacker could exploit this vulnerability by submitting a crafted file containing OLE2 content to be scanned by ClamAV on an affected device. A successful exploit could allow the attacker to terminate the ClamAV scanning process, resulting in a DoS condition on the affected software. For a description of this vulnerability, see the . Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

A vulnerability in the management and VPN web servers of Cisco Secure Firewall ASA Software and Secure FTD Software could allow an unauthenticated, remote attacker to cause the device to reload unexpectedly, resulting in a DoS condition. This vulnerability is due to improper validation of user-supplied input on an interface with VPN web services. An attacker could exploit this vulnerability by sending crafted HTTP requests to a targeted web server on an affected device. A successful exploit could allow the attacker to cause a DoS condition when the device reloads.

A vulnerability in the RADIUS proxy feature for the IPsec VPN feature of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. This vulnerability is due to improper processing of IPv6 packets. An attacker could exploit this vulnerability by sending IPv6 packets over an IPsec VPN connection to an affected device. A successful exploit could allow the attacker to trigger a reload of the device, resulting in a DoS condition.

A vulnerability in the packet inspection functionality of the Snort 3 Detection Engine of Cisco Secure Firewall 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 incorrect processing of traffic that is inspected by an affected device. An attacker could exploit this vulnerability by sending crafted traffic through the affected device. A successful exploit could allow the attacker to cause the affected device to enter an infinite loop while inspecting traffic, resulting in a DoS condition. The system watchdog will restart the Snort process automatically.

A vulnerability in the RADIUS message processing feature of Cisco Identity Services Engine (ISE) 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 RADIUS requests. An attacker could exploit this vulnerability by sending a specific authentication request to a network access device (NAD) that uses Cisco ISE for authentication, authorization, and accounting (AAA). A successful exploit could allow the attacker to cause Cisco ISE to reload.

A vulnerability in the function that performs IPv4 and IPv6 Network Address Translation (NAT) DNS inspection for Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition.  This vulnerability is due to an infinite loop condition that occurs when a Cisco Secure ASA or Cisco Secure FTD device processes DNS packets with DNS inspection enabled and the device is configured for NAT44, NAT64, or NAT46. An attacker could exploit this vulnerability by sending crafted DNS packets that match a static NAT rule with DNS inspection enabled through an affected device. A successful exploit could allow the attacker to create an infinite loop and cause the device to reload, resulting in a 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 Network-Based Application Recognition (NBAR) feature of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload, causing a denial of service (DoS) condition. This vulnerability is due to improper handling of malformed Control and Provisioning of Wireless Access Points (CAPWAP) packets. An attacker could exploit this vulnerability by sending malformed CAPWAP packets through an affected device. A successful exploit could allow the attacker to cause the device to reload unexpectedly, resulting in a DoS condition.

A vulnerability in the Internet Key Exchange version 2 (IKEv2) function of Cisco IOS XR Software could allow an unauthenticated, remote attacker to prevent an affected device from processing any control plane UDP packets.  This vulnerability is due to improper handling of malformed IKEv2 packets. An attacker could exploit this vulnerability by sending malformed IKEv2 packets to an affected device. A successful exploit could allow the attacker to prevent the affected device from processing any control plane UDP packets, resulting in a denial of service (DoS) condition. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

A vulnerability in the RADIUS setting Reject RADIUS requests from clients with repeated failures on Cisco Identity Services Engine (ISE) could allow an unauthenticated, remote attacker to cause Cisco ISE to restart unexpectedly. This vulnerability is due to a logic error when processing a RADIUS access request for a MAC address that is already a rejected endpoint. An attacker could exploit this vulnerability by sending a specific sequence of multiple crafted RADIUS access request messages to Cisco ISE. A successful exploit could allow the attacker to cause a denial of service (DoS) condition when Cisco ISE restarts.

A vulnerability in the Two-Way Active Measurement Protocol (TWAMP) server feature of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause the affected device to reload, resulting in a denial of service (DoS) condition. For Cisco IOS XR Software, this vulnerability could cause the ipsla_ippm_server process to reload unexpectedly if debugs are enabled. This vulnerability is due to out-of-bounds array access when processing specially crafted TWAMP control packets. An attacker could exploit this vulnerability by sending crafted TWAMP control packets to an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition. Note: For Cisco IOS XR Software, only the ipsla_ippm_server process reloads unexpectedly and only when debugs are enabled. The vulnerability details for Cisco IOS XR Software are as follows:    Security Impact Rating (SIR): Low    CVSS Base Score: 3.7    CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

A vulnerability in the Cisco AnyConnect VPN server of Cisco Meraki MX and Cisco Meraki Z Series Teleworker Gateway devices could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition in the Cisco AnyConnect service on an affected device. This vulnerability is due to variable initialization errors when an SSL VPN session is established. An attacker could exploit this vulnerability by sending a sequence of crafted HTTPS requests to an affected device. A successful exploit could allow the attacker to cause the Cisco AnyConnect VPN server to restart, resulting in the failure of all established SSL VPN sessions and forcing remote users to initiate a new VPN connection and re-authenticate. A sustained attack could prevent new SSL VPN connections from being established, effectively making the Cisco AnyConnect VPN service unavailable for all legitimate users.

A vulnerability in the SIP processing subsystem of Cisco BroadWorks could allow an unauthenticated, remote attacker to halt the processing of incoming SIP requests, resulting in a denial of service (DoS) condition. This vulnerability is due to improper memory handling for certain SIP requests. An attacker could exploit this vulnerability by sending a high number of SIP requests to an affected system. A successful exploit could allow the attacker to exhaust the memory that was allocated to the Cisco BroadWorks Network Servers that handle SIP traffic. If no memory is available, the Network Servers can no longer process incoming requests, resulting in a DoS condition that requires manual intervention to recover.

Cisco Adaptive Security Appliances (ASA) devices, when SMP is used, do not properly process X.509 certificates, which allows remote attackers to cause a denial of service (device crash) via a large volume of (1) SSL or (2) TLS traffic, aka Bug ID CSCuh19462.

Cisco Unified Communications Manager (Unified CM) 8.5(x) and 8.6(x) before 8.6(2a)su3 and 9.x before 9.1(1) does not properly restrict the rate of SIP packets, which allows remote attackers to cause a denial of service (memory and CPU consumption, and service disruption) via a flood of UDP packets to port 5060, aka Bug ID CSCub35869.

A vulnerability in the TCP syslog module of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to exhaust the 1550-byte buffers on an affected device, resulting in a denial of service (DoS) condition. The vulnerability is due to a missing boundary check in an internal function. An attacker could exploit this vulnerability by establishing a man-in-the-middle position between an affected device and its configured TCP syslog server and then maliciously modifying the TCP header in segments that are sent from the syslog server to the affected device. A successful exploit could allow the attacker to exhaust buffer on the affected device and cause all TCP-based features to stop functioning, resulting in a DoS condition. The affected TCP-based features include AnyConnect SSL VPN, clientless SSL VPN, and management connections such as Secure Shell (SSH), Telnet, and HTTPS.

The Location Bandwidth Manager (LBM) Intracluster-communication feature in Cisco Unified Communications Manager (CUCM) 9.x before 9.1(1) does not require authentication from the remote LBM Hub node, which allows remote attackers to conduct cache-poisoning attacks against transaction records, and cause a denial of service (bandwidth-pool consumption and call outage), via unspecified vectors, aka Bug ID CSCub28920.

Cisco Prime Central for Hosted Collaboration Solution (HCS) Assurance 8.6 and 9.0 allows remote attackers to cause a denial of service (CPU consumption and monitoring outage) via malformed TLS messages to TCP port (1) 9043 or (2) 9443, aka Bug ID CSCuc07155.

Cisco Adaptive Security Appliances (ASA) devices with software 7.x before 7.2(5.10), 8.0 before 8.0(5.31), 8.1 and 8.2 before 8.2(5.38), 8.3 before 8.3(2.37), 8.4 before 8.4(5), 8.5 before 8.5(1.17), 8.6 before 8.6(1.10), and 8.7 before 8.7(1.3) allow remote attackers to cause a denial of service (device reload) via a crafted certificate, aka Bug ID CSCuc72408.

The RSVP protocol implementation in Cisco IOS 12.2 and 15.0 through 15.2 and IOS XE 3.1.xS through 3.4.xS before 3.4.5S and 3.5.xS through 3.7.xS before 3.7.2S, when MPLS-TE is enabled, allows remote attackers to cause a denial of service (incorrect memory access and device reload) via a traffic engineering PATH message in an RSVP packet, aka Bug ID CSCtg39957.

Cisco ACE A2(3.6) allows log retention DoS.

A vulnerability in the Smart Install feature of Cisco IOS Software and Cisco 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, or to execute arbitrary code on an affected device. The vulnerability is due to improper validation of packet data. An attacker could exploit this vulnerability by sending a crafted Smart Install message to an affected device on TCP port 4786. A successful exploit could allow the attacker to cause a buffer overflow on the affected device, which could have the following impacts: Triggering a reload of the device, Allowing the attacker to execute arbitrary code on the device, Causing an indefinite loop on the affected device that triggers a watchdog crash. Cisco Bug IDs: CSCvg76186.

A vulnerability in the Bidirectional Forwarding Detection (BFD) offload implementation of Cisco Catalyst 4500 Series Switches and Cisco Catalyst 4500-X Series Switches could allow an unauthenticated, remote attacker to cause a crash of the iosd process, causing a denial of service (DoS) condition. The vulnerability is due to insufficient error handling when the BFD header in a BFD packet is incomplete. An attacker could exploit this vulnerability by sending a crafted BFD message to or across an affected switch. A successful exploit could allow the attacker to trigger a reload of the system. This vulnerability affects Catalyst 4500 Supervisor Engine 6-E (K5), Catalyst 4500 Supervisor Engine 6L-E (K10), Catalyst 4500 Supervisor Engine 7-E (K10), Catalyst 4500 Supervisor Engine 7L-E (K10), Catalyst 4500E Supervisor Engine 8-E (K10), Catalyst 4500E Supervisor Engine 8L-E (K10), Catalyst 4500E Supervisor Engine 9-E (K10), Catalyst 4500-X Series Switches (K10), Catalyst 4900M Switch (K5), Catalyst 4948E Ethernet Switch (K5). Cisco Bug IDs: CSCvc40729.

A vulnerability in the Local Packet Transport Services (LPTS) feature set of Cisco ASR 9000 Series Aggregation Services Router Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to a lack of input and validation checking on certain Precision Time Protocol (PTP) ingress traffic to an affected device. An attacker could exploit this vulnerability by injecting malformed traffic into an affected device. A successful exploit could allow the attacker to cause services on the device to become unresponsive, resulting in a DoS condition. Cisco Bug IDs: CSCvj22858.

A vulnerability in the Cisco IOS Software and Cisco IOS XE Software function that restores encapsulated option 82 information in DHCP Version 4 (DHCPv4) packets could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a Relay Reply denial of service (DoS) condition. The vulnerability exists because the affected software performs incomplete input validation of encapsulated option 82 information that it receives in DHCPOFFER messages from DHCPv4 servers. An attacker could exploit this vulnerability by sending a crafted DHCPv4 packet to an affected device, which the device would then forward to a DHCPv4 server. When the affected software processes the option 82 information that is encapsulated in the response from the server, an error could occur. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition. Cisco Bug IDs: CSCvg62754.

A vulnerability in the Control and Provisioning of Wireless Access Points (CAPWAP) protocol component of Cisco Wireless LAN Controller (WLC) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. The vulnerability is due to improper input validation on fields within CAPWAP Discovery Request packets by the affected device. An attacker could exploit this vulnerability by sending malicious CAPWAP Discovery Request packets to the Cisco WLC Software. A successful exploit could allow the attacker to cause the Cisco WLC Software to disconnect associated access points (APs). While the APs disconnect and reconnect, service will be unavailable for a brief period of time, resulting in a DoS condition.

A vulnerability in the XCP Router service of the Cisco Unified Communications Manager IM & Presence Service (CUCM IM&P) and the Cisco TelePresence Video Communication Server (VCS) and Expressway could allow an unauthenticated, remote attacker to cause a temporary service outage for all IM&P users, resulting in a denial of service (DoS) condition. The vulnerability is due to improper validation of user-supplied input. An attacker could exploit this vulnerability by sending a malicious IPv4 or IPv6 packet to an affected device on TCP port 7400. An exploit could allow the attacker to overread a buffer, resulting in a crash and restart of the XCP Router service. Cisco Bug IDs: CSCvg97663, CSCvi55947.

A vulnerability in the IPv6 subsystem of Cisco IOS XR Software Release 5.3.4 for the Cisco Aggregation Services Router (ASR) 9000 Series could allow an unauthenticated, remote attacker to trigger a reload of one or more Trident-based line cards, resulting in a denial of service (DoS) condition. The vulnerability is due to incorrect handling of IPv6 packets with a fragment header extension. An attacker could exploit this vulnerability by sending IPv6 packets designed to trigger the issue either to or through the Trident-based line card. A successful exploit could allow the attacker to trigger a reload of Trident-based line cards, resulting in a DoS during the period of time the line card takes to restart. This vulnerability affects Cisco Aggregation Services Router (ASR) 9000 Series when the following conditions are met: The router is running Cisco IOS XR Software Release 5.3.4, and the router has installed Trident-based line cards that have IPv6 configured. A software maintenance upgrade (SMU) has been made available that addresses this vulnerability. The fix has also been incorporated into service pack 7 for Cisco IOS XR Software Release 5.3.4. Cisco Bug IDs: CSCvg46800.