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

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 Impact Rating CVSS Base Score Cisco Expressway Series Remote Code Execution Vulnerability CVE-2026-76466 Critical 9.8 Cisco Expressway Series Security Hardening Release: October 2026 CVE-2026-76490 CVE-2026-76491 CVE-2026-76492 CVE-2026-76493 CVE-2026-76494 CVE-2026-76495 CVE-2026-76496 CVE-2026-76497 High 8.6 Cisco Expressway Series Information Disclosure Vulnerability CVE-2026-76435 Medium 5.3 Cisco Unified Communications Products Security Hardening Release: October 2026 CVE-2026-76476 CVE-2026-76473 CVE-2026-76475 CVE-2026-76477 CVE-2026-76478 CVE-2026-76479 CVE-2026-76481 CVE-2026-76474 Critical 9.8 Cisco Unified Communications Manager Improper Access Control Vulnerability CVE-2026-76487 Medium 5.3 Cisco IOS XR Software and Secure Client Cisco Security Advisory CVE ID Security Impact Rating CVSS Base Score Cisco IOS XR Software for ASR 9000 Series Routers IPv4 Unicast Packets Denial of Service Vulnerability CVE-2026-76505 High 7.5 Cisco Secure Client Secure Firewall Posture Module Privilege Escalation Vulnerability CVE-2026-76462 High 5.5