Vulnerability Snapshot
CVE-2026-20277 is rated CRITICAL — exploitation is trivial or already observed in the wild and impact is severe. Patch immediately, not on the next maintenance window.
Affected technology: IOS XR.
Executive Summary
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 CVE-2026-20277CVE-2026-20278CVE-2026-20280CVE-2026-20279CVE-2026-20276CVE-2026-20275CVE-2026-20274 Critical 9.8 Cisco Nexus 9000 Series Switches Silicon One Remote Code Execution Vulnerability CVE-2026-20212 Critical 9.8 Cisco Desk Phone 9800
Source
How Vulnios Detects This
Vulnios scans for this vulnerability using Trivy and Grype for SBOM-based CVE matching and Vulnios CVE feed continuous monitoring against your asset inventory. Run a scan against your environment to see whether you are exposed; findings are linked back to the original CVE record so triage starts with the patch path already known.
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Affected Products
Sources
Related Threat Alerts
- Cisco Warns of Unpatched Secure Email Flaws, Patches Critical Switch Vulnerabilities
- Cisco Desk Phone 9800 Series, IP Phone 7800 and 8800 Series, and Video Phone 8875 with SIP Software Denial of Service Vulnerability
- Cisco IOS XR Software Security Hardening Release: September 2026
- Cisco Crosswork Security Hardening Release: August 2026
- Cisco Secure Email Secure/Multipurpose Internet Mail Extensions Ciphertext Decryption Vulnerabilities
- Cisco Nexus 9000 Series Switches Silicon One Remote Code Execution Vulnerability
Frequently Asked Questions
What is CVE-2026-20277?
CVE-2026-20277 is a critical-severity vulnerability tracked under the Common Vulnerabilities and Exposures program. 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 S
Am I affected?
Check whether your environment runs IOS XR. If you operate any of those, treat yourself as in scope until you have evidence otherwise. A Vulnios scan will identify the exact assets carrying the affected version.
How urgent is the response?
Critical: do not wait for your normal patch cycle. Verify exposure today, apply the vendor patch immediately, and add detection rules for any post-exploit indicators.
How do I remediate?
Apply the vendor patch listed in the upstream advisory linked under Sources. If the patch is not yet available, follow the vendor-supplied workaround (often a config flag or feature disable) and add detections for the published exploit pattern in your SIEM. Re-scan after the patch lands to confirm the finding clears.
Where can I track exploitation activity?
Watch CISA's Known Exploited Vulnerabilities catalog for CVE-2026-20277. Cross-reference with public exploit databases and your own SIEM/IDS for indicator-of-compromise patterns. Vulnios tracks KEV status automatically and surfaces it on the asset findings view.
How does Vulnios help with this?
Vulnios continuously cross-references your asset inventory against the live CVE feed (NVD, vendor advisories, CISA KEV, and curated OSINT). When a new CVE matches your environment, you get a prioritized finding with the severity, KEV status, exploit-prediction (EPSS), and a direct path to the vendor patch. You can start a free scan from the homepage.
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