Summary

• 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.

  This vulnerability is due to improper rate limiting for syslog message 419002. 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 available at the following link:
  https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asa-ftd-logging-dos-ZXXNesfN

  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

• Vulnerable Products

  This vulnerability affects Cisco devices if they are running a vulnerable release of Cisco Secure Firewall ASA Software or Cisco Secure FTD Software and have syslog logging enabled for message 419002. Logging message 419002 is enabled by default when logging is enabled globally.

  For information about which Cisco software releases are vulnerable, see the Fixed Software section of this advisory.

  Determine the Device Configuration

  To determine whether a device is affected by this vulnerability, use the following steps.

  1. Use the show logging | include syslog logging command on the device CLI to verify if syslog logging is enabled globally. If the output of this command includes enabled, as shown in the following example, syslog logging is enabled globally. Proceed to Step 2.

  ASAv1# show logging | include syslog
  Syslog logging: enabled

  If the output indicates that logging is disabled, the device is not affected.

  2. Use the show logging message 419002 command to determine if logging is specifically enabled for syslog message 419002. If the output of this command shows that logging is enabled for syslog message 419002, note the default level that the device uses when logging this message. The following example output shows that syslog message 419002 is enabled at default level warnings. Proceed to Step 3.

  ASA# show logging message 419002
  syslog 419002: default-level warnings (enabled),standby 
  logging (disabled)

  If logging for this message is disabled, the device is not affected.

  3. Use the show logging | include logging: level command to determine if logging to any log destination is enabled and confirm the corresponding logging level.
  The following example output shows that logging is enabled for destination Console at level errors and for destination Buffer at level warnings:

  ASA# show logging | include logging: level
      Console logging: level errors, 301 messages logged
      Buffer logging: level warnings, 265964 messages logged

  If logging to any destination is enabled at the logging level that was confirmed for syslog message 419002 in Step 2 or higher, the device is affected.

  In the example in Step 3, logging to destination Buffer is configured to level warnings, which corresponds to the logging level for syslog message 419002 in the example in Step 2. The device in this example would be considered vulnerable.

  In the example in Step 3, logging to destination Console is configured at level errors, which is below the logging level for syslog message 419002 in the example in Step 2. If this were the only enabled logging destination on the device, syslog message 419002 would never be logged, and the device would not be considered vulnerable.

  Empty output of the show logging | include logging: level command indicates that the device is not affected.

  For more information on logging configuration, see the Logging chapter in CLI Book 1: Cisco Secure Firewall ASA Series General Operations CLI Configuration Guide, 9.24, the Syslog section in the Cisco Secure Firewall Management Center Device Configuration Guide, or the Configuring System Logging Settings section in the Cisco Secure Firewall Device Manager Configuration Guide.

  Products Confirmed Not Vulnerable

  Only products listed in the Vulnerable Products section of this advisory are known to be affected by this vulnerability.

  Cisco has confirmed that this vulnerability does not affect Cisco Secure Firewall Management Center (FMC) Software.

Workarounds

• There is a workaround that addresses this vulnerability. Rate limit in Cisco Secure Firewall ASA Software or Cisco Secure FTD Software using the methods described in the following sections.

  Cisco Secure Firewall ASA Software

  For devices that are running Cisco Secure Firewall ASA Software, append in global configuration mode and manually rate limit using the logging rate-limit 100 1 message 419002 command.

  In the following example, message 419002 is limited to a rate of 100 messages per second, which will prevent successful exploitation of this vulnerability:

  ASA(config)# logging rate-limit 100 1 message 419002

   

  Cisco Secure FTD Software

  For devices that are running Cisco Secure FTD Software, use one of the following options:

  • Choose Secure Firewall Management Center (FMC) > Devices > Platform Settings > Rate Limit > Syslog Level and deploy the appropriate policies. For more information, see Configure Logging on FTD via FMC.
  • Choose Firewall Device Manager (FTD) > Device > System Settings > Logging and rate limit message 419002 to 100 messages per second. For more information, see Configure and Verify Syslog in Firepower Device Manager.

  While this workaround has been deployed and was proven successful in a test environment, customers should determine the applicability and effectiveness in their own environment and under their own use conditions. Customers should be aware that any workaround or mitigation that is implemented may negatively impact the functionality or performance of their network based on intrinsic customer deployment scenarios and limitations. Customers should not deploy any workarounds or mitigations before first evaluating the applicability to their own environment and any impact to such environment.

Fixed Software

• Cisco considers any workarounds and mitigations (if applicable) to be temporary solutions until an upgrade to a fixed software release is available. To remediate this vulnerability and avoid future exposure as described in this advisory, Cisco strongly recommends that customers upgrade to the fixed software indicated in this advisory.

  Cisco Secure Firewall ASA, Secure FMC, and Secure FTD Software

  To help customers determine their exposure to vulnerabilities in Cisco Secure Firewall ASA, Secure FMC, and Secure FTD Software, Cisco provides the Cisco Software Checker. This tool identifies any Cisco security advisories that impact a specific software release and the earliest release that fixes the vulnerabilities that are described in each advisory (“First Fixed”). If applicable, the tool also returns the earliest release that fixes all the vulnerabilities that are described in all the advisories that the Software Checker identifies (“Combined First Fixed”).

  To use the tool, go to the Cisco Software Checker page and follow the instructions. Alternatively, use the following form to search for vulnerabilities that affect a specific software release. To use the form, follow these steps:

  1. Choose which advisories the tool will search—all advisories, only advisories with a Critical or High Security Impact Rating (SIR), or only this advisory.
  2. Choose the appropriate software.
  3. Choose the appropriate platform.
  4. Enter a release number—for example, 9.20.3.4 for Cisco Secure Firewall ASA Software or 7.4.2 for Cisco Secure FTD Software.
  5. Click Check.

  Only this advisory All Critical and High advisories All advisories Cisco ASA Software Cisco FMC Software Cisco FTD Software Any Platform 3000 Series Industrial Security Appliances (ISA) ASA 5500-X Series Firewalls ASA Service Module Adaptive Security Virtual Appliance (ASAv) Firepower 1000 Series Firepower 2100 Series Firepower 4100 Series Firepower 9000 Series Secure Firewall 1200 Series Secure Firewall 3100 Series Secure Firewall 4200 Series

   

  For instructions on upgrading a Cisco Secure FTD device, see the appropriate Cisco Secure FMC upgrade guide.

Exploitation and Public Announcements

• The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.

Source

• This vulnerability was found during the resolution of a Cisco Technical Assistance Center (TAC) support case.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asa-ftd-logging-dos-ZXXNesfN

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	—	Final	2026-SEP-16

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