Summary

• Multiple Cisco products are affected by vulnerabilities in the Snort 3 Detection Engine that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to restart, resulting in an interruption of packet inspection.

  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 available at the following link:
  https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snort3-multi-dos-XFWkWSwz

  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.

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

  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, this vulnerability 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 Cisco Meraki Products

  At the time of publication, the vulnerability that is described in CVE-2006-20005 affected the following products if they were running a vulnerable release of Meraki Software:

  MX64 MX64W MX65 MX65W MX67 MX67C MX67W

  MX68 MX68CW MX75 MX84 MX85 MX95

  MX100 MX105 MX250 MX400 MX450 MX600

  Impact to Other Cisco Products

  At the time of publication, the vulnerabilities that are described in CVE-2006-20005, CVE-2026-20067, and CVE-2026-20068 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 also has confirmed that these vulnerabilities do not affect the following products:

  • Cisco Secure Access Secure Internet Access (SIA) Advantage
  • Cisco Secure Access Secure Private Access (SPA) Advantage
  • Cisco Secure Firewall Adaptive Security Appliance (ASA) Software
  • Cisco Secure Firewall Management Center (FMC) Software
  • Cisco Umbrella Cloud-delivered Firewall (CDFW), formerly Umbrella Secure Internet Gateway (SIG)
  • Open Source Snort 2

  Cisco has confirmed that CVE-2006-20065, CVE-2026-20066, CVE-2026-20067, and CVE-2026-20068 do not affect Cisco Meraki products.

  Cisco has also confirmed that CVE-2006-20065 and CVE-2026-20066 do not affect Cisco Cyber Vision.

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-2026-20005: Multiple Cisco Products Snort 3 SSL Denial of Service Vulnerability

  Multiple Cisco products are affected by a vulnerability in the Snort 3 Detection Engine that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to restart, resulting in an interruption of packet inspection.

  This vulnerability is due to incomplete parsing of the SSL handshake ingress packets by the Snort 3 Detection Engine. An attacker could exploit this vulnerability by sending crafted SSL handshake packets. A successful exploit could allow the attacker to cause a denial of service (DoS) condition when the Snort 3 Detection Engine restarts unexpectedly.

  Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

  Bug ID(s): CSCwn65473 and CSCwp99280
  CVE ID: CVE-2026-20005
  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-2026-20065: Multiple Cisco Products Snort 3 Binder DoS Vulnerability

  Multiple Cisco products are affected by a vulnerability in the Snort 3 Detection Engine that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to restart, resulting in an interruption of packet inspection.

  This vulnerability is due to an error in the binder module initialization logic of the Snort Detection Engine. An attacker could exploit this vulnerability by sending certain packets through an established connection that is parsed by Snort 3. A successful exploit could allow the attacker to cause a DoS condition when the Snort 3 Detection Engine restarts unexpectedly.

  Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability. 

  Bug ID(s): CSCwn49805
  CVE ID: CVE-2026-20065
  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-2026-20066: Multiple Cisco Products Snort 3 JSTokenizer DoS Vulnerability

  Multiple Cisco products are affected by a vulnerability in the Snort 3 Detection Engine that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to restart, resulting in an interruption of packet inspection.

  This vulnerability is due to an error in the JSTokenizer normalization logic when the HTTP inspection normalizes JavaScript. An attacker could exploit this vulnerability by sending crafted HTTP packets through an established connection that is parsed by Snort 3. A successful exploit could allow the attacker to cause a DoS condition when the Snort 3 Detection Engine restarts unexpectedly. JSTokenizer is not enabled by default.

  Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

  Bug ID(s): CSCwq23374
  CVE ID: CVE-2026-20066
  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-2026-20067: Multiple Cisco Products Snort 3 Multicast DNS DoS Vulnerability

  Multiple Cisco products are affected by a vulnerability in the Snort 3 detection engine that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to restart, resulting in an interruption of packet inspection. 

  This vulnerability is due to incomplete error checking when parsing the Multicast DNS fields of the HTTP header. An attacker could exploit this vulnerability by sending crafted HTTP packets through an established connection to be parsed by Snort 3. A successful exploit could allow the attacker to cause a DoS condition when the Snort 3 Detection Engine unexpectedly restarts.

  Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

  Bug ID(s): CSCwq01530
  CVE ID: CVE-2026-20067
  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-2026-20068: Multiple Cisco Products Snort 3 RPC DoS Vulnerability

  Multiple Cisco products are affected by a vulnerability in the Snort 3 detection engine that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to restart, resulting in an interruption of packet inspection.

  This vulnerability is due to incomplete error checking when parsing remote procedure call (RPC) data. An attacker could exploit this vulnerability by sending crafted RPC packets through an established connection to be parsed by Snort 3. A successful exploit could allow the attacker to cause a DoS condition when the Snort 3 Detection Engine unexpectedly restarts.

  Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

  Bug ID(s): CSCwq01529
  CVE ID: CVE-2026-20068
  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 are no workarounds that address these vulnerabilities. 

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-2026-20005 and CVE-2026-20068	First Fixed Release for CVE-2026-20065	First Fixed Release for CVE-2026-20066	First Fixed Release for CVE-2026-20067
  3.x	3.9.2.0 and later	3.6.3.0 and later	3.9.7.0 and later	3.9.5.0 and later

   

  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

   

   

  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

  Other Platforms

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

   

  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.

  Meraki MX Security Appliances

  Snort is integrated natively into Cisco Meraki security appliances as part of the threat protection services that are managed automatically through the Meraki Dashboard. No customer action is required to download Meraki firmware or the Snort 3 package for Meraki devices. As of February 5, 2026, all Meraki models listed in this advisory that are online and connected to the Cisco Meraki Dashboard have been automatically updated with the Snort 3 package, which fixes all vulnerabilities in Snort 3 for the February 2026 Cisco Secure Firewall ASA, Secure FMC, and Secure FTD Software Security Advisory Bundled Publication.

  UTD Software: CSCwo93207, CSCwq82404, CSCwr21398, CSCwq97644, CSCwq97624

  Cisco IOS XE Software Release	First Fixed Release
  Earlier than 17.12	Not vulnerable.
  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: CSCwo93208, CSCwq97649, CSCwq03411

  Cisco Cyber Vision Release	First Fixed Release for CVE-2006-20067, CVE-2026-20067, and CVE-2026-20068
  Earlier than 5.3	Migrate to a fixed release.
  5.3	5.3.3

  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

• CVE-2026-20005 and CVE-2026-20065: These vulnerabilities were found during the resolution of a Cisco Technical Assistance Center (TAC) support case.

  CVE-2026-20066, CVE-2026-20067, and CVE-2026-20068: 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-snort3-multi-dos-XFWkWSwz

Revision History

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

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