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 AsyncOS 8.0 before 8.0.6-119 on Web Security Appliance (WSA) devices allows remote attackers to cause a denial of service (proxy-process hang) via a crafted HTTP POST request, aka Bug ID CSCuo12171.

Cisco 600 series routers running CBOS 2.0.1 through 2.4.2ap allows remote attackers to cause a denial of service via multiple connections to the router on the (1) HTTP or (2) telnet service, which causes the router to become unresponsive and stop forwarding packets.

Cisco routers and switches running IOS 12.0 through 12.2.1 allows a remote attacker to cause a denial of service via a flood of UDP packets.

Cisco IOS 12.2 and earlier running Cisco Discovery Protocol (CDP) allows remote attackers to cause a denial of service (memory consumption) via a flood of CDP neighbor announcements.

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.

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 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 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 VPN 3000 series concentrators before 2.5.2(F) allow remote attackers to cause a denial of service via an IP packet with an invalid IP option.

Cisco IOS 11.x and 12.0 with ATM support allows attackers to cause a denial of service via the undocumented Interim Local Management Interface (ILMI) SNMP community string.

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 IOS 12.1(2)T, 12.1(3)T allow remote attackers to cause a denial of service (reload) via a connection to TCP ports 3100-3999, 5100-5999, 7100-7999 and 10100-10999.

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 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 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.

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.

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 cat6000-dot1x component in Cisco IOS 12.2 before 12.2(33)SXI7 does not properly handle (1) a loop between a dot1x enabled port and an open-authentication dot1x enabled port and (2) a loop between a dot1x enabled port and a non-dot1x port, which allows remote attackers to cause a denial of service (traffic storm) via unspecified vectors that trigger many Spanning Tree Protocol (STP) Bridge Protocol Data Unit (BPDU) frames, aka Bug ID CSCtq36327.

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.

The Cisco IronPort Email Security Appliance (ESA) allows remote attackers to cause a denial of service (CPU consumption) via long Subject headers in e-mail messages, aka Bug ID CSCzv93864.

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.

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

Buffer overflow in Cisco 7xx routers through the telnet service.

Denial of service in Cisco routers running NAT via a PORT command from an FTP client to a Telnet 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.

Cisco WebEx Meetings Server 2.6 allows remote attackers to cause a denial of service (CPU consumption) by repeatedly accessing the account-validation component of an unspecified service, aka Bug ID CSCuy92704.

Cisco Catalyst LAN switches running Catalyst 5000 supervisor software allows remote attackers to perform a denial of service by forcing the supervisor module to reload.

Unspecified vulnerability in Cisco ASA 5500 Series Adaptive Security Appliance 7.0 before 7.0(8.10), 7.2 before 7.2(4.45), 8.0 before 8.0(5.1), 8.1 before 8.1(2.37), and 8.2 before 8.2(1.15); and Cisco PIX 500 Series Security Appliance; allows remote attackers to cause a denial of service (active IPsec tunnel loss and prevention of new tunnels) via a malformed IKE message through an existing tunnel to UDP port 4500, aka Bug ID CSCtc47782.

Cisco PIX firewall and CBAC IP fragmentation attack results in a denial of service.

Cisco TFTP Server 1.1 allows remote attackers to cause a denial of service (daemon crash) via a crafted (1) read (aka RRQ) or (2) write (aka WRQ) request, or other TFTP packet. NOTE: some of these details are obtained from third party information.

The web-based management interface on Cisco Small Business 220 devices with firmware before 1.0.1.1 allows remote attackers to cause a denial of service (interface outage) via a crafted HTTP request, aka Bug ID CSCuz76238.

Cisco Adaptive Security Appliances (ASA) 5500 series devices with software before 8.2(3) allow remote attackers to cause a denial of service (ASDM syslog outage) via a long URL, aka Bug IDs CSCsm11264 and CSCtb92911.

Cisco IP Phone 8800 devices with software 11.0(1) allow remote attackers to cause a denial of service (memory corruption) via a crafted HTTP request, aka Bug ID CSCuz03038.

The proxy process on Cisco Web Security Appliance (WSA) devices through 9.1.0-070 allows remote attackers to cause a denial of service (CPU consumption) by establishing an FTP session and then improperly terminating the control connection after a file transfer, aka Bug ID CSCuy43468.

Memory leak in the gk_circuit_info_do_in_acf function in the H.323 implementation in Cisco IOS before 15.0(1)XA allows remote attackers to cause a denial of service (memory consumption) via a large number of calls over a long duration, as demonstrated by InterZone Clear Token (IZCT) test traffic, aka Bug ID CSCsz72535.

A vulnerability in the email message filtering feature of Cisco AsyncOS Software for Cisco Email Security Appliances could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device.Affected Products: This vulnerability affects all releases prior to the first fixed release of Cisco AsyncOS Software for Cisco Email Security Appliances, both virtual and hardware appliances, if the software is configured to apply a message filter that contains certain rules. More Information: CSCux59873. Known Affected Releases: 8.5.6-106 9.1.0-032 9.7.0-125. Known Fixed Releases: 9.1.1-038 9.7.1-066.

A vulnerability in the Event Management Service daemon (emsd) of Cisco IOS XR routers could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on the affected device. The vulnerability is due to improper handling of gRPC requests. An attacker could exploit this vulnerability by repeatedly sending unauthenticated gRPC requests to the affected device. A successful exploit could allow the attacker to crash the device in such a manner that manual intervention is required to recover. This vulnerability affects all Cisco IOS XR platforms that are running release 6.1.1 of Cisco IOS XR Software when the gRPC service is enabled on the device. The gRPC service is not enabled by default. Cisco Bug IDs: CSCvb14441.

Cisco Unified Communications Manager IM and Presence Service 9.1(1) SU6, 9.1(1) SU6a, 9.1(1) SU7, 10.5(2) SU2, 10.5(2) SU2a, 11.0(1) SU1, and 11.5(1) allows remote attackers to cause a denial of service (sipd process restart) via crafted headers in a SIP packet, aka Bug ID CSCva39072.

Cisco IOS 15.5(3)S3, 15.6(1)S2, 15.6(2)S1, and 15.6(2)T1 does not properly dequeue invalid NTP packets, which allows remote attackers to cause a denial of service (interface wedge) by sending many crafted NTP packets, aka Bug ID CSCva35619.

Cisco IOS XR 6.0 and 6.0.1 on NCS 6000 devices allows remote attackers to cause a denial of service (OSPFv3 process reload) via crafted OSPFv3 packets, aka Bug ID CSCuz66289.

The REST interface in Cisco Spark 2015-06 allows remote attackers to cause a denial of service (resource outage) by accessing an administrative page, aka Bug ID CSCuv84125.

The Smart Install client implementation in Cisco IOS 12.2, 15.0, and 15.2 and IOS XE 3.2 through 3.7 allows remote attackers to cause a denial of service (device reload) via crafted image list parameters in a Smart Install packet, aka Bug ID CSCuv45410.

Cisco AsyncOS before 8.5.3-069 and 8.6 through 8.8 on Web Security Appliance (WSA) devices mishandles memory allocation for HTTP requests, which allows remote attackers to cause a denial of service (proxy-process reload) via a crafted request, aka Bug ID CSCuu02529.

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.

The Neighbor Discovery (ND) protocol implementation in the IPv6 stack in Cisco IOS XE 2.1 through 3.17S, IOS XR 2.0.0 through 5.3.2, and NX-OS allows remote attackers to cause a denial of service (packet-processing outage) via crafted ND messages, aka Bug ID CSCuz66542, as exploited in the wild in May 2016.

The DHCPv6 relay implementation in Cisco Adaptive Security Appliance (ASA) Software 9.4.1 allows remote attackers to cause a denial of service (device reload) via crafted DHCPv6 packets, aka Bug ID CSCus23248.

Cisco Wireless LAN Controller (WLC) Software 7.4 before 7.4.130.0(MD) and 7.5, 7.6, and 8.0 before 8.0.110.0(ED) allows remote attackers to cause a denial of service (device reload) via crafted Bonjour traffic, aka Bug ID CSCur66908.

Memory leak in Cisco AsyncOS through 8.8 on Web Security Appliance (WSA) devices allows remote attackers to cause a denial of service (memory consumption) via an unspecified HTTP status code, aka Bug ID CSCur28305.

emWEB on Cisco Adaptive Security Appliances (ASA) 5500 series devices with software before 8.2(3) allows remote attackers to cause a denial of service (daemon crash) via a request for a document whose name contains space characters, aka Bug ID CSCsy08416.