Cisco Advance Notification for Publication of September 2, 2026, Security Advisories

On September 2, 2026, the Cisco Product Security Incident Response Team (PSIRT) published the following advisories: Cisco Security Advisory CVE ID Security Impact Rating CVSS Base Score Cisco IOS XR Software Security Hardening Release: September 2026 ["https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-hardening-iosxr-qg64NcM"] CVE-2026-20277 CVE-2026-20278 CVE-2026-20280 CVE-2026-20279 CVE-2026-20276 CVE-2026-20275 CVE-2026-20274 Critical 9.8 Cisco Nexus 9000 Series Switches Silicon One Remote Code Execution Vulnerability ["https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-n9k-s1-rce-EH8dEtr"] CVE-2026-20212 Critical 9.8 Cisco Desk Phone 9800 Series, IP Phone 7800 and 8800 Series, and Video Phone 8875 with SIP Software Denial of Service Vulnerability ["https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-phone-dos-txMYNRzv"] CVE-2026-20281 High 7.5 Cisco Secure Email Secure/Multipurpose Internet Mail Extensions Ciphertext Decryption Vulnerabilities ["https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-esa-smime-disc-dzw4rEdY"] CVE-2026-20355 CVE-2026-20354 Medium 5.9 To remediate the vulnerabilities that were disclosed on September 2, 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 ["https://blogs.cisco.com/security/strengthening-the-foundation-a-predictable-customer-focused-response-to-ai-accelerated-vulnerability-discovery"].