CVE-2026-20273: Cisco IOS XE

High severity, CVSS 8.6. EPSS: 0.5% chance of exploitation in the next 30 days.

As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco IOS XE Software engineering team has conducted a comprehensive internal security review. This review resulted in a software hardening release that addresses multiple internally discovered vulnerabilities. The vulnerabilities tracked by CVE-2026-20273 are related to improper input validation issues that are grouped under the Common Weakness Enumeration (CWE) Pillar CWE-20.

Affected products

• Cisco IOS XE: version 16.6.2 only; version 16.6.3 only; version 16.6.4 only; version 16.6.4a only; version 16.6.4s only; version 16.6.5 only; …

Published 2026-08-05. Last modified 2026-10-03.