A vulnerability in the Border Gateway Protocol (BGP) over an Ethernet Virtual Private Network (EVPN) for Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause the device to reload, resulting in a denial of service (DoS) condition, or potentially corrupt the BGP routing table, which could result in network instability. The vulnerability exists due to changes in the implementation of the BGP MPLS-Based Ethernet VPN RFC (RFC 7432) draft between IOS XE software releases. When the BGP Inclusive Multicast Ethernet Tag Route or BGP EVPN MAC/IP Advertisement Route update packet is received, it could be possible that the IP address length field is miscalculated. An attacker could exploit this vulnerability by sending a crafted BGP packet to an affected device after the BGP session was established. An exploit could allow the attacker to cause the affected device to reload or corrupt the BGP routing table; either outcome would result in a DoS. The vulnerability may be triggered when the router receives a crafted BGP message from a peer on an existing BGP session. This vulnerability affects all releases of Cisco IOS XE Software prior to software release 16.3 that support BGP EVPN configurations. If the device is not configured for EVPN, it is not vulnerable. Cisco Bug IDs: CSCui67191, CSCvg52875.

The Certificate Authority Proxy Function (CAPF) service in Cisco Unified Communications Manager 5.x before 5.1(3e) and 6.x before 6.1(3) allows remote attackers to cause a denial of service (voice service outage) by sending malformed input over a TCP session in which the "client terminates prematurely."

A vulnerability in the implementation of Border Gateway Protocol (BGP) functionality in Cisco IOS XR Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected system. The vulnerability is due to incorrect processing of certain BGP update messages. An attacker could exploit this vulnerability by sending BGP update messages that include a specific set of 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 from explicitly defined peers only. 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.

A vulnerability in the implementation of the Stream Control Transmission Protocol (SCTP) on Cisco Mobility Management Entity (MME) could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an eNodeB that is connected to an affected device. The vulnerability is due to insufficient input validation of SCTP traffic. An attacker could exploit this vulnerability by leveraging a man-in-the-middle position between the eNodeB and the MME and then sending a crafted SCTP message to the MME. A successful exploit would cause the MME to stop sending SCTP messages to the eNodeB, triggering a DoS condition.

Cisco Email Security Appliance (ESA) devices with software 8.5.6-106 and 9.5.0-201 allow remote attackers to cause a denial of service (per-domain e-mail reception outage) by placing malformed DMARC policy data in DNS TXT records for a domain, aka Bug ID CSCuv14806.

A vulnerability in the Border Gateway Protocol (BGP) Multicast VPN (MVPN) implementation of Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause a BGP session to repeatedly reset, causing a partial denial of service (DoS) condition due to the BGP session being down. The vulnerability is due to incorrect parsing of a specific type of BGP MVPN update message. An attacker could exploit this vulnerability by sending this BGP MVPN update message to a targeted device. A successful exploit could allow the attacker to cause the BGP peer connections to reset, which could lead to BGP route instability and impact traffic. The incoming BGP MVPN update message is valid but is parsed incorrectly by the NX-OS device, which could send a corrupted BGP update to the configured BGP peer. Note: The Cisco implementation of BGP accepts incoming BGP traffic from only explicitly configured peers. To exploit this vulnerability, an attacker must send a specific BGP MVPN update message over an established TCP connection that appears to come from a trusted BGP peer. To do so, the attacker must obtain information about the BGP peers in the trusted network of the affected system.

A vulnerability in Cisco Webex Network Recording Player and Cisco Webex Player for Microsoft Windows could allow an attacker to cause a process crash resulting in a Denial of service (DoS) condition for the player application on an affected system. The vulnerability exists due to insufficient validation of certain elements with a Webex recording stored in either the Advanced Recording Format (ARF) or the Webex Recording Format (WRF). An attacker could exploit this vulnerability by sending a user a malicious ARF or WRF file through a link or email attachment and persuading the user to open the file with the affected software on the local system. A successful exploit could allow the attacker to cause the Webex player application to crash when trying to view the malicious file.

A vulnerability in the way Cisco Webex applications process Universal Communications Format (UCF) files could allow an attacker to cause a denial of service (DoS) condition. The vulnerability is due to insufficient validation of UCF media files. An attacker could exploit this vulnerability by sending a user a malicious UCF file through a link or email attachment and persuading the user to open the file with the affected software on the local system. A successful exploit would cause the application to quit unexpectedly.

A vulnerability in the Extensible Messaging and Presence Protocol (XMPP) feature of Cisco Meeting Server software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition for users of XMPP conferencing applications. Other applications and processes are unaffected. The vulnerability is due to improper input validation of XMPP packets. An attacker could exploit this vulnerability by sending crafted XMPP packets to an affected device. An exploit could allow the attacker to cause process crashes and a DoS condition for XMPP conferencing applications.

A vulnerability in the NX-API feature of Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause an NX-API system process to unexpectedly restart. The vulnerability is due to incorrect validation of the HTTP header of a request that is sent to the NX-API. An attacker could exploit this vulnerability by sending a crafted HTTP request to the NX-API on an affected device. A successful exploit could allow the attacker to cause a denial of service (DoS) condition in the NX-API service; however, the Cisco NX-OS device itself would still be available and passing network traffic. Note: The NX-API feature is disabled by default.

The Locator/ID Separation Protocol (LISP) implementation in Cisco IOS 15.3(3)S and earlier and IOS XE does not properly validate parameters in ITR control messages, which allows remote attackers to cause a denial of service (CEF outage and packet drops) via malformed messages, aka Bug ID CSCun73782.

Cisco IOS XR 5.1 allows remote attackers to cause a denial of service (DHCPv6 daemon crash) via a malformed DHCPv6 packet, aka Bug ID CSCuo59052.

The Session Manager component in Packet Data Network Gateway (aka PGW) in Cisco ASR 5000 Series Software 11.0, 12.0, 12.1, 12.2, 14.0, 15.0, 16.x through 16.1.2, and 17.0 allows remote attackers to cause a denial of service (process crash) via a crafted TCP packet, aka Bug ID CSCuo21914.

A vulnerability in Cisco Webex Network Recording Player and Cisco Webex Player for Microsoft Windows could allow an attacker to cause a process crash resulting in a Denial of service (DoS) condition for the player application on an affected system. The vulnerability exists due to insufficient validation of certain elements with a Webex recording stored in either the Advanced Recording Format (ARF) or the Webex Recording Format (WRF). An attacker could exploit this vulnerability by sending a user a malicious ARF or WRF file through a link or email attachment and persuading the user to open the file with the affected software on the local system. A successful exploit could allow the attacker to cause the Webex player application to crash when trying to view the malicious file. This vulnerability affects Cisco Webex Network Recording Player and Webex Player releases earlier than Release 3.0 MR3 Security Patch 2 and 4.0 MR3.

The management implementation on Cisco ONS 15454 controller cards with software 9.8 and earlier allows remote attackers to cause a denial of service (card reset) via crafted packets, aka Bug ID CSCtz50902.

The IPSec implementation in Cisco IOS allows remote attackers to cause a denial of service (MTU change and tunnel-session drop) via crafted ICMP packets, aka Bug ID CSCul29918.

The BGP implementation in Cisco NX-OS 6.2(2a) and earlier does not properly handle the interaction of UPDATE messages with IPv6, VPNv4, and VPNv6 labeled unicast-address families, which allows remote attackers to cause a denial of service (peer reset) via a crafted message, aka Bug ID CSCuj03174.

The BGP implementation in Cisco NX-OS does not properly filter AS paths, which allows remote attackers to cause a denial of service (BGP service reset and resync) via a malformed UPDATE message, aka Bug ID CSCtn13065.

The BGP implementation in Cisco NX-OS does not properly filter segment types in AS paths, which allows remote attackers to cause a denial of service (BGP service reset) via a malformed UPDATE message, aka Bug ID CSCtn13043.

A vulnerability in Cisco Webex Network Recording Player and Cisco Webex Player for Microsoft Windows could allow an attacker to cause a process crash resulting in a Denial of service (DoS) condition for the player application on an affected system. The vulnerability exists due to insufficient validation of certain elements with a Webex recording stored in either the Advanced Recording Format (ARF) or the Webex Recording Format (WRF). An attacker could exploit this vulnerability by sending a user a malicious ARF or WRF file through a link or email attachment and persuading the user to open the file with the affected software on the local system. A successful exploit could allow the attacker to cause the Webex player application to crash when trying to view the malicious file.

A vulnerability in Session Initiation Protocol (SIP) call handling of Cisco IP Phone 8800 Series devices could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition due to the SIP process unexpectedly restarting. All active phone calls are dropped as the SIP process restarts. More Information: CSCvc29353. Known Affected Releases: 11.0(0.1). Known Fixed Releases: 11.0(0)MP2.153 11.0(0)MP2.62.

A vulnerability in the web-based management interface of Cisco Video Surveillance Media Server could allow an unauthenticated, remote attacker to cause a denial of service (DoS) of the web-based management interface of an affected system. The vulnerability is due to insufficient validation of user-supplied input by the web-based management interface of the affected service. An attacker could exploit this vulnerability by persuading a user of the interface to click a malicious link. A successful exploit could allow the attacker to cause the web-based management interface to become unreachable, resulting in a DoS condition.

A vulnerability in the implementation of Border Gateway Protocol (BGP) 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 certain BGP update messages. An attacker could exploit this vulnerability by sending BGP update messages that include a specific, malformed attribute 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 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.

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 hijack an AnyConnect VPN session or cause a denial of service (DoS) condition for individual users of the AnyConnect VPN service on an affected device. This vulnerability is due to weak entropy for handlers that are used during the VPN authentication process as well as a race condition that exists in the same process. An attacker could exploit this vulnerability by correctly guessing an authentication handler and then sending crafted HTTPS requests to an affected device. A successful exploit could allow the attacker to take over the AnyConnect VPN session from a target user or prevent the target user from establishing an AnyConnect VPN session with the affected device.

A vulnerability in the session authentication functionality of the Remote Access SSL VPN feature of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to prevent users from authenticating. This vulnerability is due to insufficient entropy in the authentication process. An attacker could exploit this vulnerability by determining the handle of an authenticating user and using it to terminate their authentication session. A successful exploit could allow the attacker to force a user to restart the authentication process, preventing a legitimate user from establishing remote access VPN sessions.

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 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 IOS 12.2(15) and earlier allows remote attackers to cause a denial of service (refused VTY (virtual terminal) connections), via a crafted TCP connection to the Telnet or reverse Telnet port.

A vulnerability in an API of the Call Bridge feature of Cisco Meeting Server could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. This vulnerability is due to improper handling of large series of message requests. An attacker could exploit this vulnerability by sending a series of messages to the vulnerable API. A successful exploit could allow the attacker to cause the affected device to reload, dropping all ongoing calls and resulting in a DoS condition.

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 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.

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.

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 ingress traffic manager of Cisco IOS XE Software for Cisco Network Convergence System (NCS) 520 Routers could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition in the web management interface of an affected device. This vulnerability is due to incorrect processing of certain IPv4 TCP traffic that is destined to an affected device. An attacker could exploit this vulnerability by sending a large number of crafted TCP packets to the affected device. A successful exploit could allow the attacker to cause the web management interface to become unavailable, resulting in a DoS condition. Note: This vulnerability does not impact traffic that is going through the device or going to the Management Ethernet interface of the device.

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 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 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 Session Initiation Protocol (SIP) of Cisco Expressway Series and Cisco TelePresence Video Communication Server (VCS) could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to incorrect handling of incoming SIP traffic. An attacker could exploit this vulnerability by sending a series of SIP packets to an affected device. A successful exploit could allow the attacker to exhaust memory on an affected device, causing it to crash and leading to a DoS condition.

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.

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 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 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.

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.