CVE-2026-20276
HIGH 8.6 ALL-YEARSAs 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.
Severe if exploited (CVSS 8.6), but no confirmed exploitation. Patch on a normal cadence.
Exploitation likelihood
0.5%chance of exploitation in 30 days · 40th percentile
Impact if exploited
8.6CVSS 3.1 · HIGH · CNA
- ConfidentialityNone
- IntegrityNone
- AvailabilityHigh
What an attacker needs
- ✓Access: Reachable over the network — no local access needed
- ✓Privileges: No account or privileges required
- ✓User interaction: No user interaction needed
- ✓Complexity: No special conditions — reliably repeatable
✓ lowers the bar for an attacker · ⚠ raises it
Proof of concept
No public PoC is currently catalogued.
Search for new PoCs
Search GitHub now — results may be empty or unverified.
Tracked sources are checked weekly for the full archive, including PoCs published after the original disclosure. A later release appears after a tracked source lists it and a refresh succeeds.
Weakness (CWE)
- CWE-691: Insufficient Control Flow Management
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
References and research data (JSON)
Known Affected Software Configurations
| Vendor | Product | Version range |
|---|---|---|
| Cisco | Ios Xr | 6.5.25 |
| Cisco | Ios Xr | 6.5.26 |
| Cisco | Ios Xr | 6.5.28 |
| Cisco | Ios Xr | 6.5.29 |
| Cisco | Ios Xr | 6.5.31 |
| Cisco | Ios Xr | 6.5.32 |
| Cisco | Ios Xr | 6.5.33 |
| Cisco | Ios Xr | 6.5.35 |
| Cisco | Ios Xr | 6.5.90 |
| Cisco | Ios Xr | 6.5.351 |
| Cisco | Ios Xr | 6.5.352 |
| Cisco | Ios Xr | 6.5.353 |
| Cisco | Ios Xr | 6.7.1 |
| Cisco | Ios Xr | 6.7.2 |
| Cisco | Ios Xr | 6.7.3 |
| Cisco | Ios Xr | 6.7.4 |
| Cisco | Ios Xr | 6.7.35 |
| Cisco | Ios Xr | 6.8.1 |
| Cisco | Ios Xr | 6.8.2 |
| Cisco | Ios Xr | 6.9.1 |
| Cisco | Ios Xr | 6.9.2 |
| Cisco | Ios Xr | 7.0.0 |
| Cisco | Ios Xr | 7.0.1 |
| Cisco | Ios Xr | 7.0.2 |
| Cisco | Ios Xr | 7.0.11 |
| Cisco | Ios Xr | 7.0.12 |
| Cisco | Ios Xr | 7.0.14 |
| Cisco | Ios Xr | 7.0.90 |
| Cisco | Ios Xr | 7.1.1 |
| Cisco | Ios Xr | 7.1.2 |
| Cisco | Ios Xr | 7.1.3 |
| Cisco | Ios Xr | 7.1.15 |
| Cisco | Ios Xr | 7.1.25 |
| Cisco | Ios Xr | 7.2.0 |
| Cisco | Ios Xr | 7.2.1 |
| Cisco | Ios Xr | 7.2.2 |
| Cisco | Ios Xr | 7.2.12 |
| Cisco | Ios Xr | 7.3.1 |
| Cisco | Ios Xr | 7.3.2 |
| Cisco | Ios Xr | 7.3.3 |
| Cisco | Ios Xr | 7.3.4 |
| Cisco | Ios Xr | 7.3.5 |
| Cisco | Ios Xr | 7.3.6 |
| Cisco | Ios Xr | 7.3.15 |
| Cisco | Ios Xr | 7.3.16 |
| Cisco | Ios Xr | 7.3.27 |
| Cisco | Ios Xr | 7.4.1 |
| Cisco | Ios Xr | 7.4.2 |
| Cisco | Ios Xr | 7.4.15 |
| Cisco | Ios Xr | 7.4.16 |
| Cisco | Ios Xr | 7.5.1 |
| Cisco | Ios Xr | 7.5.2 |
| Cisco | Ios Xr | 7.5.3 |
| Cisco | Ios Xr | 7.5.4 |
| Cisco | Ios Xr | 7.5.5 |
| Cisco | Ios Xr | 7.5.12 |
| Cisco | Ios Xr | 7.5.52 |
| Cisco | Ios Xr | 7.6.1 |
| Cisco | Ios Xr | 7.6.2 |
| Cisco | Ios Xr | 7.6.3 |
| Cisco | Ios Xr | 7.6.15 |
| Cisco | Ios Xr | 7.7.1 |
| Cisco | Ios Xr | 7.7.2 |
| Cisco | Ios Xr | 7.7.21 |
| Cisco | Ios Xr | 7.8.1 |
| Cisco | Ios Xr | 7.8.2 |
| Cisco | Ios Xr | 7.8.12 |
| Cisco | Ios Xr | 7.8.22 |
| Cisco | Ios Xr | 7.8.23 |
| Cisco | Ios Xr | 7.9.1 |
| Cisco | Ios Xr | 7.9.2 |
| Cisco | Ios Xr | 7.9.21 |
| Cisco | Ios Xr | 7.10.1 |
| Cisco | Ios Xr | 7.10.2 |
| Cisco | Ios Xr | 7.11.1 |
| Cisco | Ios Xr | 7.11.2 |
| Cisco | Ios Xr | 7.11.21 |
| Cisco | Ios Xr | 24.1.1 |
| Cisco | Ios Xr | 24.1.2 |
| Cisco | Ios Xr | 24.2.1 |
| Cisco | Ios Xr | 24.2.2 |
| Cisco | Ios Xr | 24.2.11 |
| Cisco | Ios Xr | 24.2.20 |
| Cisco | Ios Xr | 24.2.21 |
| Cisco | Ios Xr | 24.3.1 |
| Cisco | Ios Xr | 24.3.2 |
| Cisco | Ios Xr | 24.3.20 |
| Cisco | Ios Xr | 24.3.30 |
| Cisco | Ios Xr | 24.4.1 |
| Cisco | Ios Xr | 24.4.2 |
| Cisco | Ios Xr | 24.4.10 |
| Cisco | Ios Xr | 24.4.15 |
| Cisco | Ios Xr | 24.4.30 |
| Cisco | Ios Xr | 25.1.1 |
| Cisco | Ios Xr | 25.1.2 |
| Cisco | Ios Xr | 25.1.30 |
| Cisco | Ios Xr | 25.2.1 |
| Cisco | Ios Xr | 25.2.2 |
| Cisco | Ios Xr | 25.2.15 |
| Cisco | Ios Xr | 25.2.30 |
| Cisco | Ios Xr | 25.3.1 |
| Cisco | Ios Xr | 25.3.15 |
| Cisco | Ios Xr | 25.4.1 |
| Cisco | Ios Xr | 25.4.2 |
| Cisco | Ios Xr | 25.4.30 |
| Cisco | Ios Xr | 25.4.201 |
| Cisco | Ios Xr | 26.1.1 |
| Cisco | Ios Xr | 26.1.2 |
| Cisco | Ios Xr | 26.2.1 |
| Cisco | Ios Xr | 26.2.100 |
| Cisco | Ios Xr | 26.2.101 |
All CVSS metrics
- HIGH 8.6 v3.1 · CNA Primary
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H - HIGH 8.6 v3.1 · NVD Secondary
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
References
Advisories
- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-hardening-iosxr-qg64NcM CVE record · cisco · Updated 2026-09-18T12:10:24.003Z
NVD · CVE-2026-20276 · Updated 2026-09-18T13:17:28.150 - https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-70203 EUVD · EUVD-2026-70203
Technical & other
- https://www.cve.org/Media/News/item/blog/2026/06/16/Preserving-Vulnerability-Level-Identification CVE record · CVE · Updated 2026-09-15T17:03:58.514Z
NVD · CVE-2026-20276 · Updated 2026-09-18T13:17:28.150
Sources: NVD · CVE.org · All sources and attribution · EPSS