The IOS HTTP service in Cisco routers and switches running IOS 11.1 through 12.1 allows remote attackers to cause a denial of service by requesting a URL that contains a %% string.

The IPsec implementation in Cisco Adaptive Security Appliance (ASA) Software 9.1 before 9.1(1.7), when an IPsec VPN tunnel is enabled, allows remote attackers to cause a denial of service (device reload) via a (1) ICMP or (2) ICMPv6 packet that is improperly handled during decryption, aka Bug ID CSCue18975.

Cisco 9900 fourth-generation IP phones do not properly perform SDP negotiation, which allows remote attackers to cause a denial of service (device reboot) via crafted SDP packets, aka Bug ID CSCuf06698.

The ALG module in Cisco IOS 15.0 through 15.4 does not properly implement SIP over NAT, which allows remote attackers to cause a denial of service (device reload) via multipart SDP IPv4 traffic, aka Bug ID CSCun54071.

Cisco IOS XR 4.3(.2) and earlier, as used in Cisco Carrier Routing System (CRS), allows remote attackers to cause a denial of service (CPU consumption and IPv6 packet drops) via a malformed IPv6 packet, aka Bug ID CSCuo95165.

Cisco TelePresence System MXP Series Software before F9.3.1 allows remote attackers to cause a denial of service (device reload) via crafted SIP packets, aka Bug ID CSCty45733.

The Application Layer Gateway (ALG) module in Cisco IOS 12.2 through 12.4 and 15.0 through 15.4, when NAT is used, allows remote attackers to cause a denial of service (device reload) via crafted DNS packets, aka Bug ID CSCue00996.

Cisco IOS XR 4.1.2 through 5.1.1 on ASR 9000 devices, when a Trident-based line card is used, allows remote attackers to cause a denial of service (NP chip and line card reload) via malformed IPv6 packets, aka Bug ID CSCun71928.

Race condition in the cut-through proxy feature in Cisco Firewall Services Module (FWSM) Software 3.x before 3.2(28) and 4.x before 4.1(15) allows remote attackers to cause a denial of service (device reload) via certain matching traffic, aka Bug ID CSCuj16824.

Cisco TelePresence ISDN Gateway with software before 2.2(1.92) allows remote attackers to cause a denial of service (D-channel call outage) via a crafted Q.931 STATUS message, aka Bug ID CSCui50360.

The produce-verbose-alert feature in Cisco IPS Software 7.1 before 7.1(8)E4 and 7.2 before 7.2(2)E4 allows remote attackers to cause a denial of service (Analysis Engine process outage) via fragmented packets, aka Bug ID CSCui91266.

The multicast listener discovery (MLD) service on Cisco Wireless LAN Controller (WLC) devices 7.2, 7.3, 7.4 before 7.4.121.0, and 7.5, when MLDv2 Snooping is enabled, allows remote attackers to cause a denial of service (device restart) via a malformed IPv6 MLDv2 packet, aka Bug ID CSCuh74233.

Cisco Adaptive Security Appliance (ASA) Software does not properly handle errors during the processing of DNS responses, which allows remote attackers to cause a denial of service (device reload) via a malformed response, aka Bug ID CSCuj28861.

Cisco IOS XE does not properly manage memory for TFTP UDP flows, which allows remote attackers to cause a denial of service (memory consumption) via TFTP (1) client or (2) server traffic, aka Bug IDs CSCuh09324 and CSCty42686.

The TLS/SSLv3 module on Cisco ONS 15454 controller cards allows remote attackers to cause a denial of service (card reset) via crafted (1) TLS or (2) SSLv3 packets, aka Bug ID CSCuh34787.

The TCP implementation in Cisco IOS does not properly implement the transitions from the ESTABLISHED state to the CLOSED state, which allows remote attackers to cause a denial of service (flood of ACK packets) via a crafted series of ACK and FIN packets, aka Bug ID CSCtz14399.

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.

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.

A vulnerability in the web UI feature of Cisco IOS XE Software could allow an unauthenticated, remote attacker to conduct a cross-site WebSocket hijacking (CSWSH) attack and cause a denial of service (DoS) condition on an affected device. This vulnerability is due to insufficient HTTP protections in the web UI on an affected device. An attacker could exploit this vulnerability by persuading an authenticated user of the web UI to follow a crafted link. A successful exploit could allow the attacker to corrupt memory on the affected device, forcing it to reload and causing a DoS condition.

A vulnerability in the implementation of the Resource Public Key Infrastructure (RPKI) feature of Cisco IOS XR Software could allow an unauthenticated, remote attacker to cause the Border Gateway Protocol (BGP) process to crash, resulting in a denial of service (DoS) condition. This vulnerability is due to the incorrect handling of a specific RPKI to Router (RTR) Protocol packet header. An attacker could exploit this vulnerability by compromising the RPKI validator server and sending a specifically crafted RTR packet to an affected device. Alternatively, the attacker could use man-in-the-middle techniques to impersonate the RPKI validator server and send a specifically crafted RTR response packet over the established RTR TCP connection to the affected device. A successful exploit could allow the attacker to cause a DoS condition because the BGP process could constantly restart and BGP routing could become unstable.Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.This advisory is part of the September 2021 release of the Cisco IOS XR Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see .

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 with the Border Gateway Protocol (BGP) for Cisco Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) mode could allow an unauthenticated, remote attacker to cause a routing process to crash, which could lead to a denial of service (DoS) condition. This vulnerability is due to an issue with the installation of routes upon receipt of a BGP update. An attacker could exploit this vulnerability by sending a crafted BGP update to an affected device. A successful exploit could allow the attacker to cause the routing process to crash, which could cause the device to reload. This vulnerability applies to both Internal BGP (IBGP) and External BGP (EBGP). Note: The Cisco implementation of BGP accepts incoming BGP traffic from explicitly configured peers only. To exploit this vulnerability, an attacker would need to send a specific BGP update message over an established TCP connection that appears to come from a trusted BGP peer.

Cisco IOS on Aironet access points, when "dot11 aaa authenticator" debugging is enabled, allows remote attackers to cause a denial of service via a malformed EAP packet, aka Bug ID CSCul15509.

Memory leak in Secure Shell (SSH) in Cisco IOS 12.0 through 12.3, when authenticating against a TACACS+ server, allows remote attackers to cause a denial of service (memory consumption) via an incorrect username or password.

Secure Shell (SSH) 2 in Cisco IOS 12.0 through 12.3 allows remote attackers to cause a denial of service (device reload) (1) via a username that contains a domain name when using a TACACS+ server to authenticate, (2) when a new SSH session is in the login phase and a currently logged in user issues a send command, or (3) when IOS is logging messages and an SSH session is terminated while the server is sending data.

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.

Cisco IOS XE 3.2 through 3.4 before 3.4.2S, and 3.5, on 1000 series Aggregation Services Routers (ASR), when bridge domain interface (BDI) is enabled, allows remote attackers to cause a denial of service (card reload) via packets that are not properly handled during the processing of encapsulation, aka Bug ID CSCtt11558.

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.

The DSP card on Cisco TelePresence MCU 4500 and 4501 devices before 4.3(2.30), TelePresence MCU MSE 8510 devices before 4.3(2.30), and TelePresence Server before 2.3(1.55) does not properly validate H.264 data, which allows remote attackers to cause a denial of service (device reload) via crafted RTP packets in a (1) SIP session or (2) H.323 session, aka Bug IDs CSCuc11328 and CSCub05448.

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.

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.

A vulnerability in the Akamai Connect feature of Cisco Wide Area Application Services (WAAS) Appliances could allow an unauthenticated, remote attacker to cause a denial-of-service (DoS) condition on an affected device. The vulnerability is due to certain file-handling inefficiencies of the affected system. An attacker could exploit this vulnerability by directing client systems to access a corrupted file that the client systems cannot decompress correctly. A successful exploit could allow the attacker to cause the affected device to crash or hang unexpectedly and result in a DoS condition that may require manual intervention to regain normal operating conditions. Cisco Bug IDs: CSCve82472.

The AAA functionality in the IPv4 SSL VPN implementations on Cisco Adaptive Security Appliances (ASA) 5500 series devices, and the ASA Services Module (ASASM) in Cisco Catalyst 6500 series devices, with software 8.2 before 8.2(5.30) and 8.3 before 8.3(2.34) allows remote attackers to cause a denial of service (device reload) via a crafted authentication response, aka Bug ID CSCtz04566.

The DCERPC inspection engine on Cisco Adaptive Security Appliances (ASA) 5500 series devices, and the ASA Services Module (ASASM) in Cisco Catalyst 6500 series devices, with software 8.3 before 8.3(2.25), 8.4 before 8.4(2.5), and 8.5 before 8.5(1.13) and the Firewall Services Module (FWSM) 4.1 before 4.1(7) in Cisco Catalyst 6500 series switches and 7600 series routers allows remote attackers to cause a denial of service (device reload) via a crafted DCERPC packet, aka Bug IDs CSCtr21376 and CSCtr27524.

The Intrusion Prevention System (IPS) feature in Cisco IOS 12.3 through 12.4 and 15.0 through 15.2, in certain configurations of enabled categories and missing signatures, allows remote attackers to cause a denial of service (device reload) via DNS packets, aka Bug ID CSCtw55976.

The BGP implementation in Cisco IOS 15.2, IOS XE 3.5.xS before 3.5.2S, and IOS XR 4.1.0 through 4.2.2 allows remote attackers to cause a denial of service (multiple connection resets) by leveraging a peer relationship and sending a malformed attribute, aka Bug IDs CSCtt35379, CSCty58300, CSCtz63248, and CSCtz62914.

Buffer overflow in the embedded HTTP server for Cisco Catalyst switches running CatOS 5.4 through 7.3 allows remote attackers to cause a denial of service (reset) via a long HTTP request.

Heap-based buffer overflow in the TFTP server capability in Cisco IOS 11.1, 11.2, and 11.3 allows remote attackers to cause a denial of service (reset) or modify configuration via a long filename.

The DCERPC inspection engine on Cisco Adaptive Security Appliances (ASA) 5500 series devices, and the ASA Services Module (ASASM) in Cisco Catalyst 6500 series devices, with software 8.3 before 8.3(2.25), 8.4 before 8.4(2.5), and 8.5 before 8.5(1.13) and the Firewall Services Module (FWSM) 4.1 before 4.1(7) in Cisco Catalyst 6500 series switches and 7600 series routers allows remote attackers to cause a denial of service (device reload) via a crafted DCERPC packet, aka Bug IDs CSCtr21346 and CSCtr27521.

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 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 IPv6 implementation of Cisco StarOS could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to insufficient validation of incoming IPv6 traffic. An attacker could exploit this vulnerability by sending a crafted IPv6 packet to an affected device with the goal of reaching the vulnerable section of the input buffer. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition. This vulnerability is specific to IPv6 traffic. IPv4 traffic is not affected.

Multiple vulnerabilities in the Zone-Based Firewall feature of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause the device to reload or stop forwarding traffic through the firewall. The vulnerabilities are due to incomplete handling of Layer 4 packets through the device. An attacker could exploit these vulnerabilities by sending a certain sequence of traffic patterns through the device. A successful exploit could allow the attacker to cause the device to reload or stop forwarding traffic through the firewall, resulting in a denial of service. For more information about these vulnerabilities, see the Details section of this advisory.

A vulnerability in the SSL/TLS inspection of Cisco Firepower Threat Defense (FTD) Software for Cisco Firepower 2100 Series firewalls could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to improper input validation for certain fields of specific SSL/TLS messages. An attacker could exploit this vulnerability by sending a malformed SSL/TLS message through an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition. No manual intervention is needed to recover the device after it has reloaded.

A vulnerability in the SIP inspection process of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a crash and reload of an affected device, resulting in a denial of service (DoS) condition. The vulnerability is due to a watchdog timeout and crash during the cleanup of threads that are associated with a SIP connection that is being deleted from the connection list. An attacker could exploit this vulnerability by sending a high rate of crafted SIP traffic through an affected device. A successful exploit could allow the attacker to cause a watchdog timeout and crash, resulting in a crash and reload of the affected device.

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.

Cisco Adaptive Security Appliance (ASA) software 7.2 and 8.2 before 8.2(5.58), 8.3 and 8.4 before 8.4(7.29), 8.5 through 8.7 before 8.7(1.17), 9.0 before 9.0(4.37), 9.1 before 9.1(6.4), 9.2 before 9.2(4), 9.3 before 9.3(3.1), and 9.4 before 9.4(1.1) allows remote attackers to cause a denial of service (device reload) via a crafted DNS response, aka Bug ID CSCut03495.

Race condition in the Zone-Based Firewall in Cisco IOS 15.1 and 15.2, when IPS policies are configured, allows remote attackers to cause a denial of service (device crash) by sending IPv6 packets, aka Bug ID CSCtk53534.

A vulnerability in the implementation of the 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. This vulnerability is due to the incorrect processing of a BGP update message that contains specific EVPN attributes. An attacker could exploit this vulnerability by sending a BGP update message that contains specific EVPN attributes. To exploit this vulnerability, an attacker must control a BGP speaker that has an established trusted peer connection to an affected device that is configured with the address family L2VPN EVPN to receive and process the update message. This vulnerability cannot be exploited by any data that is initiated by clients on the Layer 2 network or by peers that are not configured to accept the L2VPN EVPN address family. 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 updates only from explicitly defined peers. For this vulnerability to be exploited, the malicious BGP update message must either come from a configured, valid BGP peer or be injected by the attacker into the affected BGP network on an existing, valid TCP connection to a BGP peer.

The MACE feature in Cisco IOS 15.1 and 15.2 allows remote attackers to cause a denial of service (device reload) via crafted transit traffic, aka Bug IDs CSCtq64987 and CSCtu57226.