Executive brief
Cisco IOS XR is a network operating system used in core routing and network infrastructure devices. This vulnerability involves insufficient control flow management that allows an unauthenticated network attacker to cause denial of service, execute unauthorized code, or gain unauthorized access to sensitive data on affected routers and network appliances. The vulnerabilities were discovered during an internal security review and are part of a security hardening release covering multiple issues across the codebase.
Technical details
CVE-2026-20276 is grouped under CWE-691 (Insufficient Control Flow Management) and represents one of seven vulnerability classes addressed in Cisco's security hardening release. The vulnerability affects all releases of Cisco IOS XR Software with a base CVSS score of 8.6 and no authentication or user interaction required for exploitation. The attack vector is network-based, allowing an unauthenticated attacker to trigger the vulnerability remotely. Cisco has released software updates to remediate this vulnerability; however, no workarounds are available, making patching mandatory for affected systems.
Affected products
- Cisco IOS XR Software All releases including IOS XR7 (LNT)
Timeline
- 2026-09-02: disclosed: CVE-2026-20276 disclosed as part of security hardening release
- 2026-09-02: patched: Software updates released to address vulnerability