A vulnerability within the Endpoint Learning feature of Cisco Nexus 9000 Series Switches running in Application Centric Infrastructure (ACI) mode could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an endpoint device in certain circumstances. The vulnerability is due to improper endpoint learning when packets are received on a specific port from outside the ACI fabric and destined to an endpoint located on a border leaf when Disable Remote Endpoint Learning has been enabled. This can result in a Remote (XR) entry being created for the impacted endpoint that will become stale if the endpoint migrates to a different port or leaf switch. This results in traffic not reaching the impacted endpoint until the Remote entry can be relearned by another mechanism.

A vulnerability in the interactions between the DHCP and TFTP features for Cisco Small Business 300 Series (Sx300) Managed Switches could allow an unauthenticated, remote attacker to cause the device to become low on system memory, which in turn could lead to an unexpected reload of the device and result in a denial of service (DoS) condition on an affected device. The vulnerability is due to a failure to free system memory when an unexpected DHCP request is received. An attacker could exploit this vulnerability by sending a crafted DHCP packet to the targeted device. A successful exploit could allow the attacker to cause an unexpected reload of the device.

A vulnerability in the remote access VPN session manager of Cisco Adaptive Security Appliance (ASA) Software could allow a unauthenticated, remote attacker to cause a denial of service (DoS) condition on the remote access VPN services. The vulnerability is due to an issue with the remote access VPN session manager. An attacker could exploit this vulnerability by requesting an excessive number of remote access VPN sessions. An exploit could allow the attacker to cause a DoS condition.

A vulnerability 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 vulnerability is due to incorrect processing of a BGP update message that contains crafted EVPN attributes. An attacker could indirectly exploit the vulnerability by sending BGP EVPN update messages with a specific, malformed attribute to an affected system and waiting for a user on the device to display the EVPN operational routes’ status. If successful, the attacker could 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 this vulnerability, 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.

Cisco IOS before 15.3(2)T, when scansafe is enabled, allows remote attackers to cause a denial of service (latency) via SYN packets that are not accompanied by SYN-ACK packets from the Scan Safe Tower, aka Bug ID CSCub85451.

A vulnerability in the IP Service Level Agreements (IP SLA) responder and Two-Way Active Measurement Protocol (TWAMP) features of Cisco IOS XR Software could allow an unauthenticated, remote attacker to cause device packet memory to become exhausted or cause the IP SLA process to crash, resulting in a denial of service (DoS) condition. This vulnerability exists because socket creation failures are mishandled during the IP SLA and TWAMP processes. An attacker could exploit this vulnerability by sending specific IP SLA or TWAMP packets to an affected device. A successful exploit could allow the attacker to exhaust the packet memory, which will impact other processes, such as routing protocols, or crash the IP SLA process.

The Data in Motion (DMo) component in Cisco IOS 15.6(1)T and IOS XE, when the IOx feature set is enabled, allows remote attackers to cause a denial of service (out-of-bounds access) via crafted traffic, aka Bug ID CSCuy54015.

A vulnerability in the syslog processing engine of Cisco Identity Services Engine (ISE) could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to a race condition that may occur when syslog messages are processed. An attacker could exploit this vulnerability by sending a high rate of syslog messages to an affected device. A successful exploit could allow the attacker to cause the Application Server process to crash, resulting in a DoS condition.

A vulnerability in ClamAV versions prior to 0.100.2 could allow an attacker to cause a denial of service (DoS) condition. The vulnerability is due to an error related to the MEW unpacker within the "unmew11()" function (libclamav/mew.c), which can be exploited to trigger an invalid read memory access via a specially crafted EXE file.

A vulnerability in the detection engine reassembly of HTTP packets for Cisco Firepower System Software before 6.0.1 could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition due to the Snort process unexpectedly restarting. The vulnerability is due to improper handling of an HTTP packet stream. An attacker could exploit this vulnerability by sending a crafted HTTP packet stream to the detection engine on the targeted device. An exploit could allow the attacker to cause a DoS condition if the Snort process restarts and traffic inspection is bypassed or traffic is dropped.

The Data in Motion (DMo) application in Cisco IOS 15.6(1)T and IOS XE, when the IOx feature set is enabled, allows remote attackers to cause a denial of service via a crafted packet, aka Bug IDs CSCuy82904, CSCuy82909, and CSCuy82912.

A vulnerability in the SSL session cache management of Cisco Wide Area Application Services (WAAS) could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition due to high consumption of disk space. The user would see a performance degradation. More Information: CSCva03095. Known Affected Releases: 5.3(5), 6.1(1), 6.2(1). Known Fixed Releases: 5.3(5g)1, 6.2(2.32).

The FTP service in Cisco AsyncOS on Email Security Appliance (ESA) devices 9.6.0-000 through 9.9.6-026, Web Security Appliance (WSA) devices 9.0.0-162 through 9.5.0-444, and Content Security Management Appliance (SMA) devices allows remote attackers to cause a denial of service via a flood of FTP traffic, aka Bug IDs CSCuz82907, CSCuz84330, and CSCuz86065.

A vulnerability in the hardware crypto driver of Cisco IOS XE Software for Cisco 4300 Series Integrated Services Routers and Cisco Catalyst 9800-L Wireless Controllers could allow an unauthenticated, remote attacker to disconnect legitimate IPsec VPN sessions to an affected device. The vulnerability is due to insufficient verification of authenticity of received Encapsulating Security Payload (ESP) packets. An attacker could exploit this vulnerability by tampering with ESP cleartext values as a man-in-the-middle.

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 implementation of the Border Gateway Protocol (BGP) module in 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. The vulnerability is due to incorrect processing of certain BGP packets. An attacker could exploit this vulnerability by sending a crafted BGP packet. A successful exploit could allow the attacker to cause a DoS condition on the affected device.

A vulnerability in Cisco Aironet Access Point (AP) Software could allow an unauthenticated, remote attacker to cause an affected device to reload. The vulnerability is due to improper handling of clients that are trying to connect to the AP. An attacker could exploit this vulnerability by sending authentication requests from multiple clients to an affected device. A successful exploit could allow the attacker to cause the affected device to reload.

A vulnerability in the email message scanning feature of Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) could allow an unauthenticated, remote attacker to cause a temporary denial of service (DoS) condition on an affected device. The vulnerability is due to inadequate parsing mechanisms for specific email body components. An attacker could exploit this vulnerability by sending a malicious email containing a high number of shortened URLs through an affected device. A successful exploit could allow the attacker to consume processing resources, causing a DoS condition on an affected device. To successfully exploit this vulnerability, certain conditions beyond the control of the attacker must occur.

The kernel in Cisco TelePresence Server 3.0 through 4.2(4.18) on Mobility Services Engine (MSE) 8710 devices allows remote attackers to cause a denial of service (panic and reboot) via a crafted sequence of IPv6 packets, aka Bug ID CSCuu46673.

The IKEv2 implementation in Cisco IOS 15.0 through 15.6 and IOS XE 3.3 through 3.17 allows remote attackers to cause a denial of service (device reload) via fragmented packets, aka Bug ID CSCux38417.

Cisco WebEx Meetings Player T29.10, when WRF file support is enabled, allows remote attackers to cause a denial of service (application crash) via a crafted file, aka Bug ID CSCuz80455.

A vulnerability in the TCP socket code of Cisco IOS and IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload. The vulnerability is due to a state condition between the socket state and the transmission control block (TCB) state. While this vulnerability potentially affects all TCP applications, the only affected application observed so far is the HTTP server. An attacker could exploit this vulnerability by sending specific HTTP requests at a sustained rate to a reachable IP address of the affected software. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a denial of service (DoS) condition on an affected device.

A vulnerability in the connection handling function in 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 improper traffic handling when platform limits are reached. An attacker could exploit this vulnerability by sending a high rate of UDP traffic through an affected device. A successful exploit could allow the attacker to cause all new, incoming connections to be dropped, resulting in a DoS condition.

A vulnerability in the Cisco Webex Player for Webex Recording Format (WRF) files could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. An attacker could exploit this vulnerability by sending a user a link or email attachment with a malicious WRF file and persuading the user to open the file in the Cisco Webex Player. A successful exploit could cause the affected player to crash, resulting in a DoS condition. For more information about this vulnerability, see the Details section of this security advisory.

Multiple vulnerabilities exist in the Cisco Webex Network Recording Player for Advanced Recording Format (ARF) and Webex Recording Format (WRF) files. An attacker could exploit these vulnerabilities by providing a user with a malicious .arf or .wrf file via email or URL and convincing the user to launch the file in the Webex recording players. Exploitation of these vulnerabilities could cause an affected player to crash, resulting in a denial of service (DoS) condition. The Cisco Webex players are applications that are used to play back Webex meetings that have been recorded by an online meeting attendee. The Webex Network Recording Player for .arf files can be automatically installed when the user accesses a recording that is hosted on a Webex server. The Webex Player for .wrf files can be downloaded manually. These vulnerabilities affect ARF and WRF recording players available from Cisco Webex Meetings Suite sites, Cisco Webex Meetings Online sites, and Cisco Webex Meetings Server. Cisco Bug IDs: CSCvh70253, CSCvh70268, CSCvh72272, CSCvh72281, CSCvh72285, CSCvi60477, CSCvi60485, CSCvi60490, CSCvi60520, CSCvi60529, CSCvi60533.

A vulnerability in the Network Address Translation (NAT) Session Initiation Protocol (SIP) Application Layer Gateway (ALG) of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload. The vulnerability is due to improper processing of SIP packets in transit while NAT is performed on an affected device. An unauthenticated, remote attacker could exploit this vulnerability by sending crafted SIP packets via UDP port 5060 through an affected device that is performing NAT for SIP packets. 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 web user interface of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload. The vulnerability is due to a double-free-in-memory handling by the affected software when specific HTTP requests are processed. An attacker could exploit this vulnerability by sending specific HTTP requests to the web user interface of the affected software. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a denial of service (DoS) condition on an affected device. To exploit this vulnerability, the attacker must have access to the management interface of the affected software, which is typically connected to a restricted management network.

A vulnerability in the Secure Sockets Layer (SSL) Engine of Cisco Firepower System Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. The vulnerability is due to improper error handling while processing SSL traffic. An attacker could exploit this vulnerability by sending a large volume of crafted SSL traffic to the vulnerable device. A successful exploit could allow the attacker to degrade the device performance by triggering a persistent high CPU utilization condition. Cisco Bug IDs: CSCvh89340.

A vulnerability in Cisco AMP for Endpoints Mac Connector Software installed on Apple macOS 10.12 could allow an unauthenticated, remote attacker to cause a kernel panic on an affected system, resulting in a denial of service (DoS) condition. The vulnerability exists if the affected software is running in Block network conviction mode. Exploitation could occur if the system that is running the affected software starts a server process and an address in the IP blacklist cache of the affected software attempts to connect to the affected system. A successful exploit could allow the attacker to cause a kernel panic on the system that is running the affected software, resulting in a DoS condition. Cisco Bug IDs: CSCvk08192.

Cisco Web Security Appliance (WSA) 8.0.7 allows remote HTTP servers to cause a denial of service (memory consumption from stale TCP connections) via crafted responses, aka Bug ID CSCuw10426.

Cisco AsyncOS on Email Security Appliance (ESA) devices with software 8.5.6-073, 8.5.6-074, and 9.0.0-461, when clustering is enabled, allows remote attackers to cause a denial of service (clustering and SSH outage) via a packet flood, aka Bug IDs CSCur13704 and CSCuq05636.

Memory leak in the connection-manager implementation in Cisco Adaptive Security Appliance (ASA) Software 9.1(.3) and earlier allows remote attackers to cause a denial of service (multi-protocol management outage) by making multiple management session requests, aka Bug ID CSCug33233.

A vulnerability in the implementation of the system login block-for command for Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause a login process to unexpectedly restart, causing a denial of service (DoS) condition. This vulnerability is due to a logic error in the implementation of the system login block-for command when an attack is detected and acted upon. An attacker could exploit this vulnerability by performing a brute-force login attack on an affected device. A successful exploit could allow the attacker to cause a login process to reload, which could result in a delay during authentication to the affected device.

A vulnerability in the detection engine reassembly of Secure Sockets Layer (SSL) packets for Cisco Firepower System Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition because the Snort process consumes a high level of CPU resources. Affected Products: This vulnerability affects Cisco Firepower System Software running software releases 6.0.0, 6.1.0, 6.2.0, or 6.2.1 when the device is configured with an SSL policy that has at least one rule specifying traffic decryption. More Information: CSCvc58563. Known Affected Releases: 6.0.0 6.1.0 6.2.0 6.2.1.

The BGP Router process in Cisco IOS before 12.2(50)SY1 allows remote attackers to cause a denial of service (memory consumption) via vectors involving BGP path attributes, aka Bug ID CSCsw63003.

A vulnerability in the Live Data server of Cisco Unified Contact Center Enterprise could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability exists because the affected software improperly manages resources when processing inbound Live Data traffic. An attacker could exploit this vulnerability by sending multiple crafted Live Data packets to an affected device. A successful exploit could cause the affected device to run out of buffer resources, which could result in a stack overflow and cause the affected device to reload, resulting in a DoS condition. Note: The Live Data port in Cisco Unified Contact Center Enterprise devices allows only a single TCP connection. To exploit this vulnerability, an attacker would have to send crafted packets to an affected device before a legitimate Live Data client establishes a connection.

A vulnerability in the DHCP module 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 the affected device. The vulnerability is due to incorrect processing of certain DHCP packets. An attacker could exploit this vulnerability by sending a crafted DHCP packet to the affected device. A successful exploit could allow the attacker to cause a DoS condition on the affected device.

A memory leak vulnerability exists in Cisco IOS before 15.2(1)T due to a memory leak in the HTTP PROXY Server process (aka CSCtu52820), when configured with Cisco ISR Web Security with Cisco ScanSafe and User Authenticaiton NTLM configured.

Cisco IOS 11.1(x) through 11.3(x) and 12.0(x) through 12.2(x), when configured for BGP routing, allows remote attackers to cause a denial of service (device reload) via malformed BGP (1) OPEN or (2) UPDATE messages.

A vulnerability in the Common Open Policy Service (COPS) of Cisco IOS XE Software for Cisco cBR-8 Converged Broadband Routers could allow an unauthenticated, remote attacker to cause resource exhaustion, resulting in a denial of service (DoS) condition. This vulnerability is due to a deadlock condition in the code when processing COPS packets under certain conditions. An attacker could exploit this vulnerability by sending COPS packets with high burst rates to an affected device. A successful exploit could allow the attacker to cause the CPU to consume excessive resources, which prevents other control plane processes from obtaining resources and results in a DoS.

A vulnerability in the VXLAN Operation, Administration, and Maintenance (OAM) feature of Cisco NX-OS Software, known as NGOAM, 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 packets with a Transparent Interconnection of Lots of Links (TRILL) OAM EtherType. An attacker could exploit this vulnerability by sending crafted packets, including the TRILL OAM EtherType of 0x8902, to a device that is part of a VXLAN Ethernet VPN (EVPN) fabric. A successful exploit could allow the attacker to cause an affected device to experience high CPU usage and consume excessive system resources, which may result in overall control plane instability and cause the affected device to reload. Note: The NGOAM feature is disabled by default.

A vulnerability in the network stack 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 exists because the software improperly releases resources when it processes certain IPv6 packets that are destined to an affected device. An attacker could exploit this vulnerability by sending multiple crafted IPv6 packets to an affected device. A successful exploit could cause the network stack to run out of available buffers, impairing operations of control plane and management plane protocols and resulting in a DoS condition. Manual intervention would be required to restore normal operations on the affected device. For more information about the impact of this vulnerability, see the Details section of this advisory.

A vulnerability in the Internet Key Exchange version 1 (IKEv1) feature 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. The vulnerability is due to improper management of system memory. An attacker could exploit this vulnerability by sending malicious IKEv1 traffic to an affected device. A successful exploit could allow the attacker to cause a DoS condition on the affected device.

A vulnerability in the Border Gateway Protocol (BGP) additional paths feature of Cisco IOS XR Software could allow an unauthenticated, remote attacker to prevent authorized users from monitoring the BGP status and cause the BGP process to stop processing new updates, resulting in a denial of service (DOS) condition. The vulnerability is due to an incorrect calculation of lexicographical order when displaying additional path information within Cisco IOS XR Software, which causes an infinite loop. An attacker could exploit this vulnerability by sending a specific BGP update from a BGP neighbor peer session of an affected device; an authorized user must then issue a show bgp command for the vulnerability to be exploited. A successful exploit could allow the attacker to prevent authorized users from properly monitoring the BGP status and prevent BGP from processing new updates, resulting in outdated information in the routing and forwarding tables.

The OSPF functionality in Cisco IOS and IOS XE allows remote attackers to cause a denial of service (device reload) via crafted options in an LSA type 11 packet, aka Bug ID CSCui21030.

The NTP implementation in Cisco IOS 12.0 through 12.4 and 15.0 through 15.1, and IOS XE 2.1 through 3.3, does not properly handle encapsulation of multicast NTP packets within MSDP SA messages, which allows remote attackers to cause a denial of service (device reload) by leveraging an MSDP peer relationship, aka Bug ID CSCuc81226.