Summary

• Multiple Cisco products are affected by vulnerabilities in the processing of Distributed Computing Environment Remote Procedure Call (DCE/RPC) requests that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to leak sensitive information or to restart, which would result 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 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-dcerpc-vulns-J9HNF4tH

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, 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
  • Catalyst 8000V Edge Software
  • Catalyst 8200 Series Edge Platforms
  • Catalyst 8300 Series Edge Platforms
  • Catalyst 8500L Edge Platforms
  • 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
  =======================================================
  .
  .
  .

  
  

  Cisco Meraki Products

  At the time of publication, these vulnerabilities affected the following Cisco products if they were running a vulnerable release of Cisco Meraki software:

  MX67 MX67C MX67W MX68 MX68CW MX68W

  MX75 MX84 MX85 MX95 MX100 MX105

  MX250 MX400 MX450 MX600 MX Z4 MX vMX

  For information about which Cisco software releases were vulnerable at the time of publication, see the Fixed Software section of this advisory.

  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 these vulnerabilities do not affect Open Source Snort 2.

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

  • Cyber Vision
  • 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 the other 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-2026-20026: Multiple Cisco Products Snort 3 DCE/RPC Denial of Service Vulnerability

  Multiple Cisco products are affected by a vulnerability in the processing of DCE/RPC requests that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to leak sensitive information or to restart, resulting in an interruption of packet inspection.

  This vulnerability is due to an error in buffer handling logic when processing DCE/RPC requests, which can result in a buffer use-after-free read. An attacker could exploit this vulnerability by sending a large number of DCE/RPC requests through an established connection that is inspected by Snort 3. A successful exploit could allow the attacker to unexpectedly restart the Snort 3 Detection Engine, which could cause a denial of service (DoS).

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

  Bug ID(s): CSCwq75339 and CSCwr21376
  CVE ID: CVE-2026-20026
  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-2026-20027: Multiple Cisco Products Snort 3 DCE/RPC Information Disclosure Vulnerability

  Multiple Cisco products are affected by a vulnerability in the processing of DCE/RPC requests that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to leak sensitive information or to restart, resulting in an interruption of packet inspection.

  This vulnerability is due to an error in buffer handling logic when processing DCE/RPC requests, which can result in a buffer out-of-bounds read. An attacker could exploit this vulnerability by sending a large number of DCE/RPC requests through an established connection that is inspected by Snort 3. A successful exploit could allow the attacker to obtain sensitive information in the Snort 3 data stream.

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

  Bug ID(s): CSCwq75359 and CSCwr21389
  CVE ID: CVE-2026-20027
  Security Impact Rating (SIR): Medium
  CVSS Base Score: 5.3
  CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

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
  3.x	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 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

  Cisco Secure FTD Hot Fixes

  Cisco has released the following hot fixes to address these vulnerabilities. Customers can download the hot fixes from the Software Center on Cisco.com.

  Cisco Secure FTD Software Release	Hot Fix Name
  7.0	Cisco_FTD_Hotfix_FT-7.0.8.2-2.sh.REL.tar Cisco_FTD_SSP_FP1K_Hotfix_FT-7.0.8.2-2.sh.REL.tar Cisco_FTD_SSP_FP2K_Hotfix_FT-7.0.8.2-2.sh.REL.tar Cisco_FTD_SSP_Hotfix_FT-7.0.8.2-2.sh.REL.tar
  7.2	Cisco_FTD_Hotfix_HA-7.2.10.3-1.sh.REL.tar Cisco_FTD_SSP_FP1K_Hotfix_HA-7.2.10.3-1.sh.REL.tar Cisco_FTD_SSP_FP2K_Hotfix_HA-7.2.10.3-1.sh.REL.tar Cisco_FTD_SSP_FP3K_Hotfix_HA-7.2.10.3-1.sh.REL.tar Cisco_FTD_SSP_Hotfix_HA-7.2.10.3-1.sh.REL.tar

  For details about downloading and installing these hot fixes, see Cisco Firepower Hot Fix Release Notes.

  Additional Resources

  For help determining the best Cisco 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 Threat Defense Compatibility Guide

  Cisco IOS XE Software for UTD Software

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

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

  Cisco IOS XE Software Release	First Fixed Release
  17.18 and earlier	26.1.1 (Feb 2026)

  Cisco Meraki

  Cisco plans to release fixes for Cisco Meraki software in February 2026.
  
  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

• Cisco would like to thank Guy Lederfein of Trend Research of Trend Micro for reporting these vulnerabilities.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snort3-dcerpc-vulns-J9HNF4tH

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	-	Final	2026-JAN-07

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