Multiple Cisco Products Snort 3 Security Hardening Release: October 2026

Description

As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco owned Open Source Snort 3 Software engineering team has conducted a comprehensive internal security review. This review resulted in software hardening releases that address multiple internally discovered vulnerabilities. The vulnerabilities tracked by CVE-2026-20043 are related to issues concerning out-of-bounds writes that are grouped under the Common Weakness Enumeration (CWE) Base CWE-787. As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco-owned Open Source Snort 3 engineering team has conducted a comprehensive internal security review. This review resulted in software hardening releases that address multiple internally discovered vulnerabilities. These vulnerabilities were found during internal testing and are not known to be actively exploited. To assist customers in patching and to streamline the disclosure process, Cisco has grouped these issues by their underlying vulnerability class - Common Weakness Enumeration (CWE) - and assigned a single Common Vulnerabilities and Exposures Identifier (CVE ID) to each CWE grouping. Note: Cisco may publish separate security advisories that provide additional details about individual vulnerabilities that are addressed in this release. 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-hardening-snort3-ybgmhTQe 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 October 21, 2026, Security Advisories . Security Impact Rating: Critical CVE: CVE-2026-20043,CVE-2026-20236,CVE-2026-20291,CVE-2026-20356

What to do

Install the fixed versions listed in the official advisory. If you cannot update right away, apply the workarounds or mitigations it describes and limit access to the affected service.

Details

Vendor

Cisco

Product

Snort 3

CVE

CVE-2026-20043, CVE-2026-20236, CVE-2026-20291, CVE-2026-20356

Affected versions

Cisco Cyber Vision 3.0: 7 versions, from 3.0.0 to 3.0.6
Cisco Cyber Vision 3.1: 3.1.0; 3.1.1; 3.1.2
Cisco Cyber Vision 3.2: 5 versions, from 3.2.0 to 3.2.4
Cisco Cyber Vision 4.0: 4 versions, from 4.0.0 to 4.0.3
Cisco Cyber Vision 4.1: 8 versions, from 4.1.0 to 4.1.7
Cisco Cyber Vision 4.2: 7 versions, from 4.2.0 to 4.2.6
Cisco Cyber Vision 4.3: 4 versions, from 4.3.0 to 4.3.3
Cisco Cyber Vision 4.4: 4 versions, from 4.4.0 to 4.4.3
Cisco Cyber Vision 5.0: 5.0.0; 5.0.1; 5.0.2
Cisco Cyber Vision 5.1: 4 versions, from 5.1.0 to 5.1.3
Cisco Cyber Vision 5.2: 5.2.0; 5.2.1
Cisco Cyber Vision 5.3: 4 versions, from 5.3.0 to 5.3.3
Cisco Cyber Vision 5.5: 5.5.1; 5.5.2
Cisco Cyber Vision 5.6: 5.6.1
Cisco Cyber Vision 5.4: 5.4.0; 5.4.1; 5.4.2
Cisco Cyber Vision 5.7: 5.7.0; 5.7.1
Cisco Cyber Vision 5.8: 5.8.0; 5.8.1
Cisco Open Source Snort3 3.12: 3.12.1.0; 3.12.2.0
Cisco Open Source Snort3 3.1: 70 versions, from 3.1.2.0 to 3.1.84.0
Cisco Open Source Snort3 3.2: 3.2.1.0; 3.2.2.0
Cisco Open Source Snort3 3.3: 7 versions, from 3.3.0.0 to 3.3.7.0
Cisco Open Source Snort3 3.5: 3.5.0.0; 3.5.1.0; 3.5.2.0
Cisco Open Source Snort3 3.8: 3.8.1.0
Cisco Open Source Snort3 3.6: 4 versions, from 3.6.0.0 to 3.6.3.0
Cisco Open Source Snort3 3.9: 7 versions, from 3.9.0.0 to 3.9.7.0
Cisco Open Source Snort3 3.7: 5 versions, from 3.7.0.0 to 3.7.4.0
Cisco Open Source Snort3 3.10: 3.10.0.0; 3.10.1.0; 3.10.2.0
Cisco Open Source Snort3 3.11: 3.11.1.0
Cisco Secure Firewall Threat Defense (FTD) Software 7.0: 17 versions, from 7.0.0 to 7.0.9
Cisco Secure Firewall Threat Defense (FTD) Software 7.2: 18 versions, from 7.2.0 to 7.2.11 (from the advisory and NVD; check the exact builds in the official advisory)

CVSS score

9

Actively exploited

Not known at this time

Source

Cisco PSIRT – original advisory

Published

October 22, 2026

The description and the recommended action are quoted from the public advisory (the action is our generic advice); severity, exploitation status and affected versions are compiled automatically from public sources and may contain errors. The vendor's original advisory prevails: check it before taking action. This information is provided without warranty and does not replace a professional assessment.