Summary

• Multiple Cisco products are affected by vulnerabilities in the Snort 3 Visual Basic for Applications (VBA) Decompression Engine that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to unexpectedly restart, resulting in a denial of service (DoS) condition.

  For more information about these vulnerabilities, see the Details section of this advisory.

  Cisco has released software updates that address these vulnerabilities. There are workarounds that address these vulnerabilities.

  This advisory is available at the following link:
  https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-snort3-vbavuls-96UcVVed

  This advisory is part of the March 2026 release of the Cisco Secure Firewall ASA, Secure FMC, and Secure FTD Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: March 2026 Semiannual Cisco Secure Firewall ASA, Secure FMC, and Secure FTD Software Security Advisory Bundled Publication.

Affected Products

• Vulnerable Products

  For information about which products were affected by these vulnerabilities at the time of publication, see the following sections. 

  Open Source Snort 3

  At the time of publication, these vulnerabilities affected Open Source Snort 3.

  For information about which Snort releases were vulnerable at the time of publication, see the Fixed Software section of this advisory. For more information on Snort, see the Snort website.

  Cisco Secure Firewall Threat Defense Software

  At the time of publication, these vulnerabilities affected Cisco Secure Firewall Threat Defense (FTD) Software if Snort 3 was configured and at least one Snort 3 Detector was configured for VBA macro decompression. 

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

  More information about VBA macro decompression configurations is as follows:

  • VBA macro decompression is not enabled by default.
  • The first Cisco FTD Software release to support VBA decompression is Release 7.2.0. For more information, see the Firewall Management Center Features in Version 7.2.0 table.
  • VBA macro decompression is supported for IMAP, SMTP, HTTP, and POP3 Snort Inspector Engines. For more information, see the Snort 3 Inspector Reference and the Cisco Secure Firewall Management Center Snort 3 Configuration Guide, Version 7.2.

  Determine the Snort Configuration on Cisco Secure FTD Software

  On new installations of Cisco Secure FTD Software releases 7.0.0 and later, Snort 3 is running by default. On devices that were running Cisco Secure FTD Software Release 6.7.0 or earlier and were upgraded to Release 7.0.0 or later, Snort 2 is running by default.

  To determine if Snort 3 is running on Cisco Secure FTD Software, see Determine the Active Snort Version that Runs on Firepower Threat Defense (FTD). Snort 3 has to be active for these vulnerabilities to be exploited.

  Cisco IOS XE Software

  At the time of publication, these vulnerabilities affected the following Cisco products if they were running a vulnerable release of Unified Threat Defense (UTD) Snort IPS Engine for Cisco IOS XE Software or UTD Engine for Cisco IOS XE SD-WAN Software:

  • 1000 Series Integrated Services Routers (ISRs)
  • 4000 Series ISRs
  • 8100 Series Secure Routers
  • 8200 Series Secure Routers
  • 8300 Series Secure Routers
  • 8400 Series Secure Routers
  • Catalyst 8000V Edge Software
  • Catalyst 8200 Series Edge Platforms
  • Catalyst 8300 Series Edge Platforms
  • Catalyst 8500L Edge Platforms
  • Catalyst IR1800 Rugged Series Routers
  • Catalyst IR8340 Rugged Routers
  • Cloud Services Routers 1000V
  • Integrated Services Virtual Routers

  Note: UTD is not installed on these devices by default. If the UTD file is not installed, the device is not affected by these vulnerabilities.

  For information about which Cisco software releases were vulnerable at the time of publication, see the Fixed Software section of this advisory. See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information.

  Determine Whether UTD Is Enabled

  To determine whether UTD is enabled on a device, use the show utd engine standard status command. If the output shows a Yes under Running, UTD is enabled. If there is no output, the device is not affected. The following example shows the output on a device that has UTD enabled:

  Router# show utd engine standard status 
  Engine version       : 1.0.19_SV2.9.16.1_XE17.3
  Profile              : Cloud-Low
  System memory        :
               Usage  : 6.00 %
               Status : Green
  Number of engines    : 1

  
  

  Engine        Running    Health     Reason    
  ===========================================
  Engine(#1):   Yes        Green      None
  =======================================================
  .
  .
  .

   

  Impact to Other Cisco Products

  At the time of publication, the vulnerabilities CVE-2026-20053, CVE-2026-20054, and CVE-2026-20057 affected Cisco Cyber Vision.

  For information about which Cisco software releases were vulnerable at the time of publication, see the Fixed Software section of this advisory. See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information.

  Products Confirmed Not Vulnerable

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

  Cisco has confirmed that these vulnerabilities do not affect Open Source Snort 2.

  Cisco also has confirmed that these vulnerabilities do not affect the following Cisco products:

  • Meraki products
  • Secure Access - Secure Internet Access (SIA) Advantage
  • Secure Access - Secure Private Access (SPA) Advantage
  • Secure Firewall Adaptive Security Appliance (ASA) Software
  • Secure Firewall Management Center (FMC) Software
  • Umbrella Cloud-delivered Firewall (CDFW), formerly Umbrella Secure Internet Gateway (SIG)

Details

• The vulnerabilities are not dependent on one another. Exploitation of one of the vulnerabilities is not required to exploit another vulnerability. In addition, a software release that is affected by one of the vulnerabilities may not be affected by the other vulnerabilities.

  Details about the vulnerabilities are as follows:

  CVE-2026-20053: Cisco Secure FTD Software Snort 3 VBA Heap Overflow DoS Vulnerability

  Multiple Cisco products are affected by a vulnerability in the Snort 3 VBA feature that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to crash.

  This vulnerability is due to improper range checking when decompressing VBA data, which is user controlled. An attacker could exploit this vulnerability by sending crafted VBA data to the Snort 3 Detection Engine on the targeted device. A successful exploit could allow the attacker to cause an overflow of heap data, which could cause a DoS condition.

  Cisco has released software updates that address this vulnerability. There is a workaround that addresses this vulnerability.

  Bug ID(s): CSCwq23373, CSCwq97494, and CSCwq97497
  CVE ID: CVE-2026-20053
  Security Impact Rating (SIR): Medium
  CVSS Base Score: 5.8
  CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L

  CVE-2026-20054: Cisco Secure FTD Software Snort 3 VBA Infinite Loop DoS Vulnerability

  Multiple Cisco products are affected by a vulnerability in the Snort 3 VBA feature that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to crash. 

  This vulnerability is due to improper error checking when decompressing VBA data. An attacker could exploit this vulnerability by sending crafted VBA data to the Snort 3 Detection Engine on the targeted device. A successful exploit could allow the attacker to cause the Snort 3 Detection Engine to enter an infinite loop, causing a DoS condition.

  Cisco has released software updates that address this vulnerability. There is a workaround that addresses this vulnerability.

  Bug ID(s): CSCwq23372, CSCwq97748, and CSCwq97750
  CVE ID: CVE-2026-20054
  Security Impact Rating (SIR): Medium
  CVSS Base Score: 5.8
  CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L

  CVE-2026-20057 and CVE-2026-20058: Cisco Secure FTD Software Snort 3 VBA DoS Vulnerability

  Multiple Cisco products are affected by vulnerabilities in the Snort 3 VBA feature that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to crash.

  These vulnerabilities are due to improper error checking when decompressing VBA data. An attacker could exploit these vulnerabilities by sending crafted VBA data to the Snort 3 Detection Engine on the targeted device. A successful exploit could allow the attacker to cause the Snort 3 Detection Engine to unexpectedly restart, causing a DoS condition.

  Cisco has released software updates that address these vulnerabilities. There is a workaround that addresses these vulnerabilities.

  Bug ID(s): CSCwq23369, CSCwr21406, CSCwq23377, CSCwq97658, and CSCwq97660
  CVE ID: CVE-2026-20057 and CVE-2026-20058
  Security Impact Rating (SIR): Medium
  CVSS Base Score: 5.8
  CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L

Workarounds

• There is a workaround that addresses these vulnerabilities.

  The vulnerabilities described in this advisory are due to VBA decompression, which is not enabled by default for any Snort 3 Inspector. If VBA decompression is disabled until the device can be upgraded to a fixed software release, the device will not be affected by these vulnerabilities. For further details on how to remove the VBA configuration, see the following references:

  • Firewall Management Center Features in Version 7.2.0 
  • Snort 3 Inspector Reference
  • Cisco Secure Firewall Management Center Snort 3 Configuration Guide, Version 7.2

  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 fully remediate these vulnerabilities and avoid future exposure as described in this advisory, Cisco strongly recommends that customers upgrade to the fixed software indicated in this advisory.

  Fixed Releases

  For information about fixed releases, see the following sections. 

  Open Source Snort Software

  At the time of publication, the release information in the following table was accurate.

  Snort 3 Release	First Fixed Release for CVE-2026-20053, CVE-2026-20054, and CVE-2026-20057	First Fixed Release for CVE-2026-20058
  2.x	Not vulnerable.	Not vulnerable.
  3.x	3.9.3.0	3.9.6.0

   

  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 advisoryAll Critical and High advisoriesAll advisoriesCisco ASA SoftwareCisco FMC SoftwareCisco FTD SoftwareAny Platform3000 Series Industrial Security Appliances (ISA)ASA 5500-X Series FirewallsASA Service ModuleAdaptive Security Virtual Appliance (ASAv)Firepower 1000 SeriesFirepower 2100 SeriesFirepower 4100 SeriesFirepower 9000 SeriesSecure Firewall 1200 SeriesSecure Firewall 3100 SeriesSecure Firewall 4200 Series

   

   

  Additional Resources

  For help determining the best Cisco Secure Firewall ASA, Secure FMC, or Secure FTD Software release, see the following Recommended Releases documents. If a security advisory recommends a later release, Cisco recommends following the advisory guidance.

  Cisco Secure Firewall ASA Compatibility
  Cisco Secure Firewall ASA Upgrade Guide
  Cisco Secure Firewall Threat Defense Compatibility Guide

  Cisco IOS XE Software for UTD Software: CSCwq97494, CSCwq97748, CSCwq97658, and CSCwr21406

  At the time of publication, the release information in the following table was accurate. See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information.

  The left column lists Cisco software releases, and the right column indicates whether a release was affected by the vulnerabilities that are described in this advisory and which release included the fix for these vulnerabilities.

  Cisco IOS XE Software Release	First Fixed Release
  17.12	17.12.7 (Mar 2026)
  17.15	17.15.5
  17.18	17.18.3 (Apr 2026)
  26.1	26.1.1 (Mar 2026)

   

  Cyber Vision: CSCwq97497, CSCwq97750, and CSCwq97660

  At the time of publication, the release information in the following table was accurate. See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information.

  The left column lists Cisco software releases, and the center and right columns indicate whether a release was affected by the vulnerabilities that are described in this advisory and which release included the fix for these vulnerabilities.

  Cisco Cyber Vision Release	First Fixed Release for CVE-2026-20053, CVE-2026-20054 and CVE-2026-20057	First Fixed Release for CVE-2026-20058
  Earlier than 5.3	Migrate to a fixed release.	Not vulnerable.
  5.3	5.3.3	Not vulnerable.

  The Cisco Product Security Incident Response Team (PSIRT) validates only the affected and fixed release information that is documented in this advisory.

Exploitation and Public Announcements

• The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerabilities that are described in this advisory.

Source

• These vulnerabilities were found during internal security testing by Jason Crowder of the Cisco Advanced Security Initiatives Group (ASIG).

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-snort3-vbavuls-96UcVVed

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	—	Final	2026-MAR-04

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