Cisco Advance Notification for Publication of October 21, 2026, Security Advisories

Description

On October 21, 2026, the Cisco Product Security Incident Response Team (PSIRT) published the following advisories. To remediate the vulnerabilities that were disclosed on October 21, 2026, Cisco strongly recommends that customers upgrade to the fixed software that is indicated in the advisories. For more information about changes in Cisco PSIRT vulnerability disclosure, see Strengthening the Foundation: A Predictable, Customer-Focused Response to AI-Accelerated Vulnerability Discovery . Snort 3 Cisco Security Advisory CVE ID Security Impact Rating CVSS Base Score Multiple Cisco Products Snort 3 Security Hardening Release: October 2026 CVE-2026-20043 CVE-2026-20236 CVE-2026-20291 CVE-2026-20356 Critical 9.0 Open Source Snort 3 Control Channel Socket Arbitrary Command Execution Vulnerability CVE-2026-76524 High 7.8 Multiple Cisco Products Snort 3 Denial of Service Vulnerabilities CVE-2026-76489 CVE-2026-20019 CVE-2026-20179 CVE-2026-20197 Medium 5.8 Multiple Cisco Products Snort 3 Generic Routing Encapsulation Denial of Service Vulnerability CVE-2026-20221 Medium 5.8 Multiple Cisco Products Snort 3 SMTP MIME Denial of Service Vulnerability CVE-2026-20011 Medium 5.8 Multiple Cisco Products Snort 3 Visual Basic for Applications Buffer Overflow Denial of Service Vulnerability CVE-2026-20218 Medium 5.8 Multiple Cisco Products Snort 3 Denial of Service Vulnerability CVE-2026-76445 Medium 5.3 Cisco Expressway and Unified Communications Products Cisco Security Advisory CVE ID Security I Security Impact Rating: Informational

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, Cisco Expressway

CVE

CVE-2026-20043, CVE-2026-20236, CVE-2026-20291, CVE-2026-20356, CVE-2026-76524, CVE-2026-76489, CVE-2026-20019, CVE-2026-20179, CVE-2026-20197, CVE-2026-20221, CVE-2026-20011, CVE-2026-20218, CVE-2026-76445

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 21, 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.