Cisco Security Advisories & CVEs
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High [CVE-2024-20260] Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software SSL VPN Denial of Service Vulnerability
Update for September 16, 2026: The original 1.0 version of this advisory was specific to the Cisco Adaptive Security Virtual Appliance (ASAv) and Cisco Secure Firewall Threat Defense Virtual (FTDv) models. However, it was later found that this vulnerability affects all Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software platforms. A vulnerability in the VPN and management web servers of the Cisco Secure Firewall ASA Software and Cisco Secure FTD Software platforms could allow an unauthenticated, remote attacker to cause an affected device to run out of system memory or buffer blocks, which in turn could cause SSL VPN connection processing to slow down and eventually cease altogether. This vulnerability is due to a lack of proper memory management for new incoming SSL/TLS connections. An attacker could exploit this vulnerability by sending a large number of new incoming SSL/TLS connections to the targeted device. A successful exploit could allow the attacker to deplete system memory or buffers, resulting in a denial of service (DoS) condition. The memory or buffers could be reclaimed slowly if the attack traffic is stopped, but a manual reload may be required to restore operations quickly. Cisco has released software updates that address this vulnerability.
High [CVE-2026-20250] Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software for Secure Firewall 3100 and 4200 Series DTLS Denial of Service Vulnerability
A vulnerability in Datagram TLS (DTLS) message handling of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software for Cisco Secure Firewall 3100 Series and 4200 Series devices could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper resource management when processing certain DTLS messages. An attacker could exploit this vulnerability by sending a crafted stream of DTLS traffic to an affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition. Cisco has released software updates that address this vulnerability. There are workarounds that address this vulnerability. This advisory is part of a group of advisories. For a complete list of the advisories and links to them, see Cisco Advance Notification for Publication of September 16, 2026, Security Advisories. In addition, for further documentation of improvements and fixes in Cisco Secure Firewall products, see Cisco Secure Firewall Adaptive Security Appliance Software, Secure Firewall Threat Defense Software, and Secure Firewall Management Center Software Hardening Release: September 2026. Affected products named by the advisory: Secure Firewall 4200 Series.
High [CVE-2026-20352] Cisco Identity Services Engine RADIUS Denial of Service Vulnerability
A vulnerability in the RADIUS feature of Cisco Identity Services Engine (ISE) 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 certain RADIUS requests. An attacker could exploit this vulnerability by sending a crafted RADIUS request directly to an affected device. A successful exploit could allow the attacker to cause the ISE node to become unavailable. For single node deployments in that condition, endpoints that have not already authenticated would be unable to access the network until the node comes back up on its own. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability. This advisory is part of a group of advisories. For a complete list of the advisories and links to them, see Cisco Advance Notification for Publication of September 16, 2026, Security Advisories. In addition, for further documentation of improvements and fixes in Cisco Identity Services Engine, see Cisco Identity Services Engine Security Hardening Release: September 2026. Affected product named by the advisory: Identity Services Engine Software.
High [CVE-2026-20295 +1] Cisco Secure Firewall Management Center and Secure Firewall Threat Defense Software sftunnel Vulnerabilities
Multiple vulnerabilities in Cisco Secure Firewall Management Center (FMC) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated attacker to perform an sftunnel authentication bypass or sftunnel denial of service (DoS) attack. For more information about these vulnerabilities, see the Details section of this advisory. Cisco has released software updates that address these vulnerabilities. There are no workarounds that address these vulnerabilities. This advisory is part of a group of advisories. For a complete list of the advisories and links to them, see Cisco Advance Notification for Publication of September 16, 2026, Security Advisories. In addition, for further documentation of improvements and fixes in Cisco Secure Firewall products, see Cisco Secure Firewall Adaptive Security Appliance Software, Secure Firewall Threat Defense Software, and Secure Firewall Management Center Software Hardening Release: September 2026. Affected products named by the advisory: Firepower 2100 Series; Firepower 1000 Series; ASA 5500-X Series Firewalls; 3000 Series Industrial Security Appliances (ISA); and 3 more.
High [CVE-2026-20135] Cisco Secure Firewall Threat Defense Software TLS 1.3 Denial of Service Vulnerability
A vulnerability in the TLS 1.3 implementation in Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause an affected device to reload unexpectedly, resulting in a denial of service (DoS) condition. This vulnerability is due to improper buffer management during the TLS 1.3 connection. An attacker could exploit this vulnerability by sending a crafted TLS 1.3 packet to an affected system through a TLS 1.3-enabled listening socket. A successful exploit could allow the attacker to cause the LINA process to crash, which would cause the device to reload. The reload can happen before or after authentication of the connection. Note: TLS 1.3 connections include both data traffic and user-management traffic. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability. This advisory is part of a group of advisories. For a complete list of the advisories and links to them, see Cisco Advance Notification for Publication of September 16, 2026, Security Advisories. In addition, for further documentation of improvements and fixes in Cisco Secure Firewall products, see Cisco Secure Firewall Adaptive Security Appliance Software, Secure Firewall Threat Defense Software, and Secure Firewall Management Center Software Hardening Release: September 2026.
High [CVE-2026-20222] Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software EIGRP Denial of Service Vulnerability
A vulnerability in the EIGRP implementation in Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, adjacent attacker to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition. This vulnerability is due to improper resource management when handling EIGRP update messages. An attacker could exploit this vulnerability by sending crafted EIGRP updates at a high rate to an affected device. A successful exploit could allow the attacker to trigger a memory leak that will eventually cause the affected device to reload unexpectedly. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability. This advisory is part of a group of advisories. For a complete list of the advisories and links to them, see Cisco Advance Notification for Publication of September 16, 2026, Security Advisories. In addition, for further documentation of improvements and fixes in Cisco Secure Firewall products, see Cisco Secure Firewall Adaptive Security Appliance Software, Secure Firewall Threat Defense Software, and Secure Firewall Management Center Software Hardening Release: September 2026.
High [CVE-2026-20154] Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software Logging Denial of Service Vulnerability
A vulnerability in the system rate-limiting process for syslog message 419002 of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause high CPU utilization on an affected device, resulting in a denial of service (DoS) condition. An attacker could exploit this vulnerability by sending a flood of TCP synchronization (SYN) packets to an affected device. A successful exploit could allow the attacker to cause high CPU utilization, resulting in performance degradation. Cisco has released software updates that address this vulnerability. There are workarounds that address this vulnerability. This advisory is part of a group of advisories. For a complete list of the advisories and links to them, see Cisco Advance Notification for Publication of September 16, 2026, Security Advisories. In addition, for further documentation of improvements and fixes in Cisco Secure Firewall products, see Cisco Secure Firewall Adaptive Security Appliance Software, Secure Firewall Threat Defense Software, and Secure Firewall Management Center Software Hardening Release: September 2026. Affected products named by the advisory: Firepower 2100 Series; Firepower 1000 Series; ASA 5500-X Series Firewalls; 3000 Series Industrial Security Appliances (ISA); and 3 more.
High [CVE-2026-20249] Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software IKEv2 Certificate Authentication Denial of Service Vulnerability
A vulnerability in the certification authentication feature of Internet Key Exchange version 2 (IKEv2) for Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause an affected device to reload unexpectedly. This vulnerability is due to a logic error during the certificate authentication phase of the IKEv2 connection setup. An attacker could exploit this vulnerability by attempting to establish an IKEv2 VPN connection with a crafted certificate. A successful exploit could allow the attacker to cause the IKEv2 process to crash, causing a denial of service (DoS) condition. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability. This advisory is part of a group of advisories. For a complete list of the advisories and links to them, see Cisco Advance Notification for Publication of September 16, 2026, Security Advisories. In addition, for further documentation of improvements and fixes in Cisco Secure Firewall products, see Cisco Secure Firewall Adaptive Security Appliance Software, Secure Firewall Threat Defense Software, and Secure Firewall Management Center Software Hardening Release: September 2026.
High [CVE-2026-20247 +1] Cisco Identity Services Engine SQL Injection Vulnerabilities
Multiple vulnerabilities in Cisco Identity Services Engine (ISE) could allow a remote attacker to conduct SQL injection attacks on an affected device. For more information about these vulnerabilities, see the Details section of this advisory. Cisco has released software updates that address these vulnerabilities. There are no workarounds that address these vulnerabilities. This advisory is part of a group of advisories. For a complete list of the advisories and links to them, see Cisco Advance Notification for Publication of September 16, 2026, Security Advisories. In addition, for further documentation of improvements and fixes in Cisco Identity Services Engine, see Cisco Identity Services Engine Security Hardening Release: September 2026. Affected product named by the advisory: Identity Services Engine Software.
High [CVE-2026-20293] Cisco UCS and UCS-Based Appliances UEFI Shell Secure Boot Bypass Vulnerability
A vulnerability in the Unified Extensible Firmware Interface (UEFI) Shell implementation of Cisco UCS Servers and UCS-based appliances could allow an authenticated attacker with valid credentials for a user account with the role of user or admin or an unauthenticated attacker with physical access to an affected device to bypass UEFI Secure Boot validation checks and execute unauthorized software. This vulnerability is due to the availability of memory write commands in the UEFI Shell while UEFI Secure Boot is enabled on a device. An attacker could exploit this vulnerability by selecting the UEFI Shell boot option at boot time and using available shell commands to modify UEFI memory variables. A successful exploit could allow the attacker to manipulate the preboot environment, overwrite UEFI Secure Boot-related memory values, and execute unauthorized software on the affected device. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability. Affected products named by the advisory: Unified Computing System E-Series Software (UCSE); Unified Computing System (Managed); Unified Computing System (Standalone); Enterprise NFV Infrastructure Software.
High [CVE-2026-20281] Cisco Desk Phone 9800 Series, IP Phone 7800 and 8800 Series, and Video Phone 8875 with SIP Software Denial of Service Vulnerability
A vulnerability in Cisco Desk Phone 9800 Series, Cisco IP Phone 7800 and 8800 Series, and Cisco Video Phone 8875 that are running Cisco Session Initiation Protocol (SIP) 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 memory management when an affected device processes HTTP packets. An attacker could exploit this vulnerability by sending a continuous stream of crafted HTTP packets to the device. A successful exploit could allow the attacker to cause the affected device to continuously consume memory, resulting in a DoS condition. A manual reboot of the device is required to recover from this condition. Note: For this vulnerability to be exploitable, the phone must be registered to Cisco Unified Communications Manager (Unified CM) and have Web Access enabled. Web Access is disabled by default. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.
High [CVE-2026-20320] Cisco BroadWorks Out-of-Band Blind XML External Entity Injection Vulnerability
A vulnerability in the Open Client Interface (OCI) XML Parser of Cisco BroadWorks could allow an unauthenticated, remote attacker to read sensitive configuration information on an affected system. This vulnerability exists because XML entries are improperly parsed due to external entity resolution being allowed by default. An attacker could exploit this vulnerability by sending a crafted XML message to the Open Client Interface – Provisioning (OCI-P) service. A successful exploit could allow the attacker to view sensitive files from the filesystem with the privileges of the Cisco BroadWorks user. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.
High [CVE-2026-20349] Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software Remote Access SSL VPN Denial of Service Vulnerability
A vulnerability in the Remote Access SSL VPN service for Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition. This vulnerability is due to insufficient error checking when processing HTTP requests. An attacker could exploit this vulnerability by sending a crafted HTTP request to the Remote Access SSL VPN service on an affected device. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability. This advisory is part of a group of advisories. For a complete list of the advisories and links to them, see Cisco Advance Notification for Publication of September 16, 2026, Security Advisories. In addition, for further documentation of improvements and fixes in Cisco Secure Firewall products, see Cisco Secure Firewall Adaptive Security Appliance Software, Secure Firewall Threat Defense Software, and Secure Firewall Management Center Software Hardening Release: September 2026. Affected products named by the advisory: Firepower 2100 Series; Firepower 1000 Series; ASA 5500-X Series Firewalls; 3000 Series Industrial Security Appliances (ISA); and 3 more.
High [CVE-2026-20337 +6] ClamAV Vulnerabilities Affecting Cisco Products: August 2026
Multiple vulnerabilities in ClamAV could allow a remote attacker to cause a denial of service (DoS) condition, interrupting scanning operations. For more information about these vulnerabilities, see the Details section of this advisory. For additional information on these vulnerabilities in ClamAV, see the ClamAV blog. Cisco has released software updates that address these vulnerabilities in affected Cisco platforms. There are no workarounds that address these vulnerabilities. Notes: - The Security Impact Rating (SIR) for these vulnerabilities is High for Windows-based platforms only because those platforms run the ClamAV scanning process in a privileged security context. The platforms that are highly impacted include Cisco Secure Endpoint Connector for Windows. - The SIR for these vulnerabilities is Medium on other platforms, including Linux and Mac platforms, because those platforms run the ClamAV scanning process in a lower-privileged security context. The affected platforms include Secure Endpoint Connector for Linux and Mac. - Cisco Secure Endpoint Private Cloud itself is not impacted by these vulnerabilities. However, the Cisco Secure Endpoint Connector software that is distributed from the device is impacted.
High [CVE-2026-20263] Cisco IOS XE Software Blocks Extensible Exchange Protocol Denial of Service Vulnerability
A vulnerability in the Blocks Extensible Exchange Protocol (BEEP) feature of Cisco IOS XE 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 handling when parsing a specific BEEP SOAP request. An attacker could exploit this vulnerability by sending a specific BEEP SOAP request to an affected device. A successful exploit could allow the attacker to cause the device to reload unexpectedly, resulting in a DoS condition. Cisco has released software updates that address this vulnerability. There are no workarounds that address these vulnerabilities.
High [CVE-2026-20124] Cisco IOS XE Software SNMP Denial of Service Vulnerability
A vulnerability in the Simple Network Management Protocol (SNMP) subsystem of Cisco IOS XE Software could allow an authenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition. This vulnerability is due to improper error handling when parsing SNMP requests. This vulnerability affects all versions of SNMP — Versions 1, 2c, and 3. An attacker could exploit this vulnerability by sending a malformed SNMP request to an affected device. A successful exploit could allow the attacker to cause the device to reload unexpectedly. The attacker must have the SNMPv1 or v2c read-only or read-write community string or valid SNMPv3 user credentials on the affected device. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability. There is a mitigation that addresses this vulnerability.
High [CVE-2026-20301] Cisco IOS Software and IOS XE Software Extensible Messaging Client Protocol Denial of Service Vulnerability
A vulnerability in the Extensible Messaging Client Protocol (XMCP), also referred to as the External Client protocol, of Cisco IOS Software and Cisco IOS XE 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 handling of malformed XMCP packets. An attacker could exploit this vulnerability by sending a malformed XMCP packet to an affected device. A successful exploit could allow the attacker to cause the affected device to reload unexpectedly, resulting in a DoS condition. The attacker does not need the XMCP client username to exploit this vulnerability. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability. There is a mitigation that addresses this vulnerability.
High [CVE-2026-20200 +1] Cisco Integrated Management Controller Argument Injection Vulnerabilities
Multiple vulnerabilities in the web-based management interface of Cisco Integrated Management Controller (IMC) could allow an authenticated, remote attacker to execute arbitrary commands on the underlying operating system of an affected system and elevate privileges to root. For more information about these vulnerabilities, see the Details section of this advisory. Cisco has released software updates that address these vulnerabilities. There are no workarounds that address these vulnerabilities. Affected products named by the advisory: Unified Computing System (Standalone); Unified Computing System E-Series Software (UCSE).
High [CVE-2026-20028 +21] Cisco Advance Notification for Publication of August 5, 2026, Security Advisories
On August 5, 2026, the Cisco Product Security Incident Response Team (PSIRT) published the following advisories: Cisco Security Advisory CVE ID Security Impact Rating CVSS Base Score Cisco Catalyst SD-WAN Software Security Hardening Release: August 2026 CVE-2026-20303 CVE-2026-20304 CVE-2026-20310 CVE-2026-20312 CVE-2026-20313 Critical 9.9 Cisco IOS XE Software Security Hardening Release: August 2026 CVE-2026-20267 CVE-2026-20268 CVE-2026-20269 CVE-2026-20270 CVE-2026-20271 CVE-2026-20272 CVE-2026-20273 Critical 9.8 Cisco Integrated Management Controller Argument Injection Vulnerabilities CVE-2026-20200 CVE-2026-20288 High 8.8 Cisco IOS Software and IOS XE Software Extensible…
High [CVE-2026-20150 +5] Cisco RoomOS Security Hardening Release: July 2026
As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco RoomOS engineering team has conducted a comprehensive internal security review. This review resulted in a software hardening release that addresses multiple internally discovered vulnerabilities. Affected product named by the advisory: RoomOS Software.