The LAN-to-LAN IPSEC capability for Cisco VPN 3000 Concentrator 2.2.x, and 3.x before 3.5.4, allows remote attackers to cause a denial of service via an incoming LAN-to-LAN connection with an existing security association with another device on the remote network, which causes the concentrator to remove the previous connection.

Cisco VPN 3000 Concentrator 2.2.x, 3.6(Rel), and 3.x before 3.5.5, allows remote attackers to cause a denial of service via (1) malformed or (2) large ISAKMP packets.

Buffer overflows in Cisco Virtual Private Network (VPN) Client 3.5.4 and earlier allows remote attackers to cause a denial of service via (1) an Internet Key Exchange (IKE) with a large Security Parameter Index (SPI) payload, or (2) an IKE packet with a large number of valid payloads.

Cisco ONS15454 optical transport platform running ONS 3.1.0 to 3.2.0 allows remote attackers to cause a denial of service (reset) by sending IP packets with non-zero Type of Service (TOS) bits to the Timing Control Card (TCC) LAN interface.

Cisco NX-OS on the Nexus 1000V does not assign the proper priority to heartbeat messages from a Virtual Ethernet Module (VEM) to a Virtual Supervisor Module (VSM), which allows remote attackers to cause a denial of service (false VEM unavailability report) via a flood of UDP packets, aka Bug ID CSCud14840.

Cisco VPN 3000 Concentrator 2.2.x, and 3.x before 3.5.3, allows remote attackers to cause a denial of service (crash) via a long (1) username or (2) password to the HTML login interface.

The web management interface for Cisco Content Service Switch (CSS) 11000 switches allows remote attackers to cause a denial of service (soft reset) via (1) an HTTPS POST request, or (2) malformed XML data.

Cisco Aironet before 11.21 with Telnet enabled allows remote attackers to cause a denial of service (reboot) via a series of login attempts with invalid usernames and passwords.

Web-based configuration utility in Cisco 600 series routers running CBOS 2.0.1 through 2.4.2ap binds itself to port 80 even when web-based configuration services are disabled, which could leave the router open to attack.

Cisco SN 5420 Storage Router 1.1(3) and earlier allows remote attackers to cause a denial of service (reboot) via a series of connections to TCP port 8023.

Cisco Catalyst 2900XL switch allows a remote attacker to create a denial of service via an empty UDP packet sent to port 161 (SNMP) when SNMP is disabled.

Cisco CBOS 2.3.8 and earlier allows remote attackers to cause a denial of service via an ICMP ECHO REQUEST (ping) with the IP Record Route option set.

Multiple Cisco networking products allow remote attackers to cause a denial of service on the local network via a series of ARP packets sent to the router's interface that contains a different MAC address for the router, which eventually causes the router to overwrite the MAC address in its ARP table.

Cisco 12000 with IOS 12.0 and line cards based on Engine 2 and earlier allows remote attackers to cause a denial of service (CPU consumption) by flooding the router with traffic that generates a large number of ICMP Unreachable replies.

Cisco 600 routers running CBOS 2.4.1 and earlier allow remote attackers to cause a denial of service via a large ICMP echo (ping) packet.

Cisco CBOS 2.3.8 and earlier allows remote attackers to cause a denial of service via a series of large ICMP ECHO REPLY (ping) packets, which cause it to enter ROMMON mode and stop forwarding packets.

Cisco PIX Firewall 515 and 520 with 5.1.4 OS running aaa authentication to a TACACS+ server allows remote attackers to cause a denial of service via a large number of authentication requests.

Cisco devices IOS 12.0 and earlier allow a remote attacker to cause a crash, or bad route updates, via malformed BGP updates with unrecognized transitive attribute.

Cisco Catalyst 6000, 5000, or 4000 switches allow remote attackers to cause a denial of service by connecting to the SSH service with a non-SSH client, which generates a protocol mismatch error.

Cisco Catalyst 5000 series switches 6.1(2) and earlier will forward an 802.1x frame on a Spanning Tree Protocol (STP) blocked port, which causes a network storm and a denial of service.

Cisco 12000 with IOS 12.0 and line cards based on Engine 2 does not handle the "fragment" keyword in a compiled ACL (Turbo ACL) for packets that are sent to the router, which allows remote attackers to cause a denial of service via a flood of fragments.

CBOS 2.4.1 and earlier in Cisco 600 routers allows remote attackers to cause a denial of service via a slow stream of TCP SYN packets.

Buffer overflow in Cisco TACACS+ tac_plus server allows remote attackers to cause a denial of service via a malformed packet with a long length field.

Cisco IOS 11.x and 12.x allows remote attackers to cause a denial of service by sending the ENVIRON option to the Telnet daemon before it is ready to accept it, which causes the system to reboot.

The traffic engineering (TE) processing subsystem in Cisco IOS XR allows remote attackers to cause a denial of service (process restart) via crafted TE packets, aka Bug ID CSCue04000.

A vulnerability in the Shell Access Filter feature of Cisco Firepower Management Center (FMC), when used in conjunction with remote authentication, could allow an unauthenticated, remote attacker to cause high disk utilization, resulting in a denial of service (DoS) condition. The vulnerability occurs because the configuration of the Shell Access Filter, when used with a specific type of remote authentication, can cause a system file to have unbounded writes. An attacker could exploit this vulnerability by sending a steady stream of remote authentication requests to the appliance when the specific configuration is applied. Successful exploitation could allow the attacker to increase the size of a system log file so that it consumes most of the disk space. The lack of available disk space could lead to a DoS condition in which the device functions could operate abnormally, making the device unstable.

Cisco Gigabit Switch Routers (GSR) with Fast Ethernet / Gigabit Ethernet cards, from IOS versions 11.2(15)GS1A up to 11.2(19)GS0.2 and some versions of 12.0, do not properly handle line card failures, which allows remote attackers to bypass ACLs or force the interface to stop forwarding packets.

The HTTP server in Cisco IOS 12.0 through 12.1 allows local users to cause a denial of service (crash and reload) via a URL containing a "?/" string.

The JTapi Gateway process in Cisco Unified Contact Center Enterprise, Unified Contact Center Hosted, IP Contact Center Enterprise, and Cisco IP Contact Center Hosted 5.0 through 7.1 allows remote attackers to cause a denial of service (repeated process restart) via a certain TCP session on the JTapi server port.

Attackers can crash a Cisco IOS router or device, provided they can get to an interactive prompt (such as a login). This applies to some IOS 9.x, 10.x, and 11.x releases.

Land IP denial of service.

Cisco IOS 12.0 and other versions can be crashed by malicious UDP packets to the syslog port.

Vulnerability in Cisco 7xx series routers allows a remote attacker to cause a system reload via a TCP connection to the router's TELNET port.

Denial of service in Cisco IOS web server allows attackers to reboot the router using a long URL.

A vulnerability in the detection engine of Cisco Firepower System Software could allow an unauthenticated, remote attacker to cause one of the detection engine processes to run out of memory and thus slow down traffic processing. The vulnerability is due to improper handling of traffic when the Secure Sockets Layer (SSL) inspection policy is enabled. An attacker could exploit this vulnerability by sending malicious traffic through an affected device. An exploit could allow the attacker to increase the resource consumption of a single instance of the Snort detection engine on an affected device. This will lead to performance degradation and eventually the restart of the affected Snort process. Cisco Bug IDs: CSCvi09219, CSCvi29845.

A vulnerability in the Server Message Block Version 2 (SMBv2) and Version 3 (SMBv3) protocol implementation for the Cisco Firepower System Software could allow an unauthenticated, remote attacker to cause the device to run low on system memory, possibly preventing the device from forwarding traffic. It is also possible that a manual reload of the device may be required to clear the condition. The vulnerability is due to incorrect SMB header validation. An attacker could exploit this vulnerability by sending a custom SMB file transfer through the targeted device. A successful exploit could cause the device to consume an excessive amount of system memory and prevent the SNORT process from forwarding network traffic. This vulnerability can be exploited using either IPv4 or IPv6 in combination with SMBv2 or SMBv3 network traffic.

A vulnerability in the TCP throttling process of Cisco Prime Network could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to insufficient rate limiting protection for TCP listening ports. An attacker could exploit this vulnerability by sending the affected device a high rate of TCP SYN packets to the local IP address of the targeted application. A successful exploit could allow the attacker to cause the device to consume a high amount of memory and become slow, or to stop accepting new TCP connections to the application. Cisco Bug IDs: CSCvg48152.

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 management interface access control list (ACL) configuration of Cisco NX-OS System Software could allow an unauthenticated, remote attacker to bypass configured ACLs on the management interface. This could allow traffic to be forwarded to the NX-OS CPU for processing, leading to high CPU utilization and a denial of service (DoS) condition. The vulnerability is due to a bad code fix in the 7.3.2 code train that could allow traffic to the management interface to be misclassified and not match the proper configured ACLs. An attacker could exploit this vulnerability by sending crafted traffic to the management interface. An exploit could allow the attacker to bypass the configured management interface ACLs and impact the CPU of the targeted device, resulting in a DoS condition. This vulnerability affects the following Cisco products running Cisco NX-OS System Software: Multilayer Director Switches, Nexus 2000 Series Switches, Nexus 3000 Series Switches, Nexus 5500 Platform Switches, Nexus 5600 Platform Switches, Nexus 6000 Series Switches, Nexus 7000 Series Switches, Nexus 7700 Series Switches, Nexus 9000 Series Switches in standalone NX-OS mode. Cisco Bug IDs: CSCvf31132.

A vulnerability in the netconf interface of Cisco IOS XR Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on affected system. The vulnerability is due to improper handling of malformed requests processed by the netconf process. An attacker could exploit this vulnerability by sending malicious requests to the affected software. An exploit could allow the attacker to cause the targeted process to restart, resulting in a DoS condition on the affected system. Cisco Bug IDs: CSCvg95792.

A vulnerability in the Cisco Fabric Services component of Cisco FXOS Software and Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on the affected device. The vulnerability exists because the affected software insufficiently validates Cisco Fabric Services packets. An attacker could exploit this vulnerability by sending a crafted Cisco Fabric Services packet to an affected device. A successful exploit could allow the attacker to force a NULL pointer dereference and cause a DoS condition. This vulnerability affects the following if configured to use Cisco Fabric Services: Firepower 4100 Series Next-Generation Firewalls, Firepower 9300 Security Appliance, MDS 9000 Series Multilayer Switches, Nexus 2000 Series Fabric Extenders, Nexus 3000 Series Switches, Nexus 3500 Platform Switches, Nexus 5500 Platform Switches, Nexus 5600 Platform Switches, Nexus 6000 Series Switches, Nexus 7000 Series Switches, Nexus 7700 Series Switches, Nexus 9000 Series Switches in standalone NX-OS mode, Nexus 9500 R-Series Line Cards and Fabric Modules, UCS 6100 Series Fabric Interconnects, UCS 6200 Series Fabric Interconnects, UCS 6300 Series Fabric Interconnects. Cisco Bug IDs: CSCvd69966, CSCve02435, CSCve04859, CSCve41590, CSCve41593, CSCve41601.

A vulnerability in the Interactive Voice Response (IVR) management connection interface for Cisco Unified Customer Voice Portal (CVP) could allow an unauthenticated, remote attacker to cause the IVR connection to disconnect, creating a system-wide denial of service (DoS) condition. The vulnerability is due to improper handling of a TCP connection request when the IVR connection is already established. An attacker could exploit this vulnerability by initiating a crafted connection to the IP address of the targeted CVP device. An exploit could allow the attacker to disconnect the IVR to CVP connection, creating a DoS condition that prevents the CVP from accepting new, incoming calls while the IVR automatically attempts to re-establish the connection to the CVP. This vulnerability affects Cisco Unified Customer Voice Portal (CVP) Software Release 11.5(1). Cisco Bug IDs: CSCve70560.

A vulnerability in IPv6 ingress packet processing for Cisco UCS Central Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition due to high CPU utilization on the targeted device. The vulnerability is due to insufficient rate limiting protection for IPv6 ingress traffic. An attacker could exploit this vulnerability by sending the affected device a high rate of IPv6 packets. Successful exploitation could allow the attacker to cause a DoS condition due to CPU and resource constraints. Cisco Bug IDs: CSCuv34544.

The Cisco Small Business 200 Series Smart Switch 1.2.7.76 and earlier, Small Business 300 Series Managed Switch 1.2.7.76 and earlier, and Small Business 500 Series Stackable Managed Switch 1.2.7.76 and earlier allow remote attackers to cause a denial of service (SSL/TLS layer outage) via malformed (1) SSH or (2) SSL packets, aka Bug ID CSCua30246.

A vulnerability in the detection engine of Cisco Firepower System Software could allow an unauthenticated, remote attacker to restart an instance of the Snort detection engine on an affected device, resulting in a brief denial of service (DoS) condition. The vulnerability is due to the incorrect handling of a Transport Layer Security (TLS) extension during TLS connection setup for the affected software. An attacker could exploit this vulnerability by sending a crafted TLS connection setup request to an affected device. A successful exploit could allow the attacker to cause the Snort detection engine on the affected device to restart, resulting in a DoS condition. Cisco Bug IDs: CSCvg97808.

A vulnerability in the forwarding information base (FIB) code of Cisco IOS XR Software could allow an unauthenticated, remote attacker to cause inconsistency between the routing information base (RIB) and the FIB, resulting in a denial of service (DoS) condition. The vulnerability is due to incorrect processing of extremely long routing updates. An attacker could exploit this vulnerability by sending a large routing update. A successful exploit could allow the attacker to trigger inconsistency between the FIB and the RIB, resulting in a DoS condition. Cisco Bug IDs: CSCus84718.

Cisco Unified Communications Domain Manager allows remote attackers to cause a denial of service (CPU consumption) via a flood of malformed UDP packets, aka Bug ID CSCug47057.

Cisco ACE A2(3.6) allows log retention DoS.

A vulnerability in the TCP stack of Cisco SocialMiner could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition in the notification system. The vulnerability is due to faulty handling of new TCP connections to the affected application. An attacker could exploit this vulnerability by sending a malicious TCP packet to the vulnerable service. An exploit could allow the attacker to create a DoS condition by interrupting certain phone services. A manual restart of the service may be required to restore full functionalities. Cisco Bug IDs: CSCvh48368.

Cisco NX-OS on the Nexus 7000, when a certain Overlay Transport Virtualization (OTV) configuration is used, allows remote attackers to cause a denial of service (M1-Series module reload) via crafted packets, aka Bug ID CSCud15673.