Cisco IOS XR Software vulnerability

What happened

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-2026-20276 are related to insufficient control flow management issues that are grouped under the Common Weakness Enumeration (CWE) CWE-691.

Affected versions

Cisco IOS XR Software: 6.5.29; 7.0.1; 6.5.26; 6.5.25; 6.5.28; 6.5.90; 7.1.1; 7.0.90; 6.7.1; 7.0.2; 7.1.15; 7.2.1; 7.1.2; 6.7.2; 7.0.11; 7.0.12; 7.0.14; 7.1.25; 7.2.12; 7.3.1; 7.1.3; 6.7.3; 7.4.1; 7.2.2; 6.7.4; 6.5.31; 7.3.15; 7.3.16; 6.8.1; 7.4.15; 6.5.32; 7.3.2; 7.5.1; 7.4.16; 7.3.27; 7.6.1; 7.5.2; 7.8.1; 7.6.15; 7.5.12; 7.8.12; 7.3.3; 7.7.1; 6.8.2; 7.3.4; 7.4.2; 6.7.35; 6.9.1; 7.6.2; 7.5.3; 7.7.2; 6.9.2; 7.9.1; 7.10.1; 7.8.2; 7.5.4; 6.5.33; 7.8.22; 7.7.21; 7.9.2; 7.3.5; 7.5.5; 7.11.1; 7.9.21; 7.10.2; 24.1.1; 7.6.3; 7.3.6; 7.5.52; 7.11.2; 24.2.1; 24.1.2; 24.2.11; 24.3.1; 24.4.1; 24.2.2; 7.8.23; 7.11.21; 24.2.20; 24.3.2; 24.4.10; 6.5.35; 25.1.1; 24.4.2; 24.3.20; 24.4.15; 25.2.1; 6.5.351; 25.1.2; 24.3.30; 25.3.1; 6.5.352; 24.4.30; 24.2.21; 25.4.1; 25.2.2; 25.2.15; 7.2.0; 7.0.0; 25.2.30; 6.5.353; 26.1.1; 25.1.30; 25.3.15; 26.2.100; 25.4.2; 26.2.1; 25.4.30; 26.1.2; 25.4.201; 26.2.101 Fixed: See vendor advisory.

Why it matters

Review the vendor advisory and exposure of the affected product to determine operational impact.

Detection & mitigation

• Apply vendor-provided updates or mitigations.
• Review affected product exposure and access logs.