CVE-2026-20277: Cisco IOS XR Software

High severity, CVSS 8.2. EPSS: 0.2% chance of exploitation in the next 30 days.

As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco IOS XR Software engineering team has conducted a comprehensive internal security review. This review resulted in a software hardening releases that address multiple internally discovered vulnerabilities. The vulnerabilities tracked by CVE-2026-20277 are related to protection mechanism failure issues that are grouped under the Common Weakness Enumeration (CWE) CWE-693.

Affected products

• Cisco Cisco IOS XR Software: version 6.5.29 only; version 7.0.1 only; version 6.5.26 only; version 6.5.25 only; version 6.5.28 only; version 6.5.90 only; …

Published 2026-09-02. Last modified 2026-09-18.