# CVE-2026-20271

## Summary

- **CVE ID:** CVE-2026-20271
- **Severity:** HIGH
- **CVSS Score:** 8.6 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H)
- **CWE:** CWE-691
- **Published:** Aug 5, 2026
- **Last Modified:** Aug 14, 2026

## Description

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 software hardening releases that address multiple internally discovered vulnerabilities.

The vulnerabilities tracked by CVE-2026-20271 are related to insufficient control flow management issues that are grouped under the Common Weakness Enumeration (CWE) Pillar CWE-691.
 

## Affected Products

- Cisco — Cisco IOS XE Software (17.2.1a)
- Cisco — Cisco IOS XE Software (16.12.1y)
- Cisco — Cisco IOS XE Software (16.12.3s)
- Cisco — Cisco IOS XE Software (16.7.1b)
- Cisco — Cisco IOS XE Software (16.6.2)
- Cisco — Cisco IOS XE Software (16.6.5)
- Cisco — Cisco IOS XE Software (16.12.1w)
- Cisco — Cisco IOS XE Software (16.9.1d)
- Cisco — Cisco IOS XE Software (17.3.1)
- Cisco — Cisco IOS XE Software (16.9.4c)
- Cisco — Cisco IOS XE Software (16.7.1)
- Cisco — Cisco IOS XE Software (17.2.1)
- Cisco — Cisco IOS XE Software (16.6.8)
- Cisco — Cisco IOS XE Software (16.9.1b)
- Cisco — Cisco IOS XE Software (16.9.2s)
- Cisco — Cisco IOS XE Software (16.12.4)
- Cisco — Cisco IOS XE Software (16.12.3a)
- Cisco — Cisco IOS XE Software (17.1.1s)
- Cisco — Cisco IOS XE Software (16.11.1a)
- Cisco — Cisco IOS XE Software (16.7.2)
- Cisco — Cisco IOS XE Software (16.11.1b)
- Cisco — Cisco IOS XE Software (16.9.1s)
- Cisco — Cisco IOS XE Software (16.9.3h)
- Cisco — Cisco IOS XE Software (16.9.1c)
- Cisco — Cisco IOS XE Software (16.6.5a)
- Cisco — Cisco IOS XE Software (16.6.3)
- Cisco — Cisco IOS XE Software (16.10.1f)
- Cisco — Cisco IOS XE Software (17.2.1v)
- Cisco — Cisco IOS XE Software (16.8.1e)
- Cisco — Cisco IOS XE Software (16.9.3a)
- Cisco — Cisco IOS XE Software (16.12.1a)
- Cisco — Cisco IOS XE Software (16.12.1x)
- Cisco — Cisco IOS XE Software (16.6.4s)
- Cisco — Cisco IOS XE Software (16.10.1c)
- Cisco — Cisco IOS XE Software (16.12.3)
- Cisco — Cisco IOS XE Software (16.11.2)
- Cisco — Cisco IOS XE Software (16.6.5b)
- Cisco — Cisco IOS XE Software (16.12.2s)
- Cisco — Cisco IOS XE Software (16.10.1b)
- Cisco — Cisco IOS XE Software (16.7.3)
- Cisco — Cisco IOS XE Software (16.6.7)
- Cisco — Cisco IOS XE Software (16.9.6)
- Cisco — Cisco IOS XE Software (16.9.2)
- Cisco — Cisco IOS XE Software (16.10.1)
- Cisco — Cisco IOS XE Software (16.12.1t)
- Cisco — Cisco IOS XE Software (16.9.1)
- Cisco — Cisco IOS XE Software (16.8.1a)
- Cisco — Cisco IOS XE Software (16.9.3s)
- Cisco — Cisco IOS XE Software (16.6.7a)
- Cisco — Cisco IOS XE Software (16.12.2)
- Cisco — Cisco IOS XE Software (16.11.1)
- Cisco — Cisco IOS XE Software (16.9.3)
- Cisco — Cisco IOS XE Software (16.11.1s)
- Cisco — Cisco IOS XE Software (16.12.1)
- Cisco — Cisco IOS XE Software (17.1.1)
- Cisco — Cisco IOS XE Software (17.1.2)
- Cisco — Cisco IOS XE Software (16.10.1d)
- Cisco — Cisco IOS XE Software (17.1.1t)
- Cisco — Cisco IOS XE Software (16.9.4)
- Cisco — Cisco IOS XE Software (16.8.3)
- Cisco — Cisco IOS XE Software (16.12.2t)
- Cisco — Cisco IOS XE Software (16.9.5)
- Cisco — Cisco IOS XE Software (16.8.1s)
- Cisco — Cisco IOS XE Software (16.10.1e)
- Cisco — Cisco IOS XE Software (16.8.2)
- Cisco — Cisco IOS XE Software (16.6.4)
- Cisco — Cisco IOS XE Software (16.8.1b)
- Cisco — Cisco IOS XE Software (16.10.1a)
- Cisco — Cisco IOS XE Software (16.12.1z)
- Cisco — Cisco IOS XE Software (16.8.1c)
- Cisco — Cisco IOS XE Software (16.9.1a)
- Cisco — Cisco IOS XE Software (16.9.5f)
- Cisco — Cisco IOS XE Software (16.6.4a)
- Cisco — Cisco IOS XE Software (16.10.1g)
- Cisco — Cisco IOS XE Software (16.8.1)
- Cisco — Cisco IOS XE Software (16.6.6)
- Cisco — Cisco IOS XE Software (16.9.2a)
- Cisco — Cisco IOS XE Software (16.8.1d)
- Cisco — Cisco IOS XE Software (16.10.3)
- Cisco — Cisco IOS XE Software (16.7.1a)
- Cisco — Cisco IOS XE Software (16.11.1c)
- Cisco — Cisco IOS XE Software (16.10.1s)
- Cisco — Cisco IOS XE Software (17.2.1r)
- Cisco — Cisco IOS XE Software (17.1.1a)
- Cisco — Cisco IOS XE Software (16.10.2)
- Cisco — Cisco IOS XE Software (16.12.2a)
- Cisco — Cisco IOS XE Software (16.12.1c)
- Cisco — Cisco IOS XE Software (16.12.1s)
- Cisco — Cisco IOS XE Software (16.7.4)
- Cisco — Cisco IOS XE Software (17.2.2)
- Cisco — Cisco IOS XE Software (16.9.8)
- Cisco — Cisco IOS XE Software (16.9.7)
- Cisco — Cisco IOS XE Software (17.1.3)
- Cisco — Cisco IOS XE Software (17.3.1a)
- Cisco — Cisco IOS XE Software (17.3.2a)
- Cisco — Cisco IOS XE Software (16.12.5)
- Cisco — Cisco IOS XE Software (17.3.1w)
- Cisco — Cisco IOS XE Software (17.3.2)
- Cisco — Cisco IOS XE Software (17.4.1)
- Cisco — Cisco IOS XE Software (16.12.4a)
- Cisco — Cisco IOS XE Software (17.4.1a)
- Cisco — Cisco IOS XE Software (17.3.1x)
- Cisco — Cisco IOS XE Software (17.3.3)
- Cisco — Cisco IOS XE Software (16.6.9)
- Cisco — Cisco IOS XE Software (17.2.3)
- Cisco — Cisco IOS XE Software (17.5.1)
- Cisco — Cisco IOS XE Software (16.12.1z1)
- Cisco — Cisco IOS XE Software (16.12.5a)
- Cisco — Cisco IOS XE Software (17.4.1b)
- Cisco — Cisco IOS XE Software (17.3.1z)
- Cisco — Cisco IOS XE Software (16.12.5b)
- Cisco — Cisco IOS XE Software (17.4.2)
- Cisco — Cisco IOS XE Software (17.3.3a)
- Cisco — Cisco IOS XE Software (17.3.5)
- Cisco — Cisco IOS XE Software (17.3.4)
- Cisco — Cisco IOS XE Software (17.5.1a)
- Cisco — Cisco IOS XE Software (16.12.6)
- Cisco — Cisco IOS XE Software (17.6.1)
- Cisco — Cisco IOS XE Software (16.12.1z2)
- Cisco — Cisco IOS XE Software (16.6.10)
- Cisco — Cisco IOS XE Software (17.3.4a)
- Cisco — Cisco IOS XE Software (17.6.1a)
- Cisco — Cisco IOS XE Software (17.7.1)
- Cisco — Cisco IOS XE Software (17.6.1x)
- Cisco — Cisco IOS XE Software (17.6.2)
- Cisco — Cisco IOS XE Software (16.12.6a)
- Cisco — Cisco IOS XE Software (17.3.4c)
- Cisco — Cisco IOS XE Software (17.4.2a)
- Cisco — Cisco IOS XE Software (17.3.4b)
- Cisco — Cisco IOS XE Software (17.7.1a)
- Cisco — Cisco IOS XE Software (16.12.7)
- Cisco — Cisco IOS XE Software (17.8.1a)
- Cisco — Cisco IOS XE Software (17.6.3a)
- Cisco — Cisco IOS XE Software (17.6.3)
- Cisco — Cisco IOS XE Software (17.7.2)
- Cisco — Cisco IOS XE Software (17.7.1b)
- Cisco — Cisco IOS XE Software (17.9.1w)
- Cisco — Cisco IOS XE Software (17.3.5a)
- Cisco — Cisco IOS XE Software (17.6.1z)
- Cisco — Cisco IOS XE Software (16.12.8)
- Cisco — Cisco IOS XE Software (17.8.1)
- Cisco — Cisco IOS XE Software (17.9.1)
- Cisco — Cisco IOS XE Software (17.6.4)
- Cisco — Cisco IOS XE Software (17.3.5b)
- Cisco — Cisco IOS XE Software (17.9.1a)
- Cisco — Cisco IOS XE Software (17.3.6)
- Cisco — Cisco IOS XE Software (17.10.1)
- Cisco — Cisco IOS XE Software (16.9.8a)
- Cisco — Cisco IOS XE Software (17.6.1z1)
- Cisco — Cisco IOS XE Software (17.10.1a)
- Cisco — Cisco IOS XE Software (17.9.2)
- Cisco — Cisco IOS XE Software (17.6.5)
- Cisco — Cisco IOS XE Software (17.9.1x)
- Cisco — Cisco IOS XE Software (17.9.1y)
- Cisco — Cisco IOS XE Software (16.9.8b)
- Cisco — Cisco IOS XE Software (17.3.7)
- Cisco — Cisco IOS XE Software (17.9.2a)
- Cisco — Cisco IOS XE Software (17.9.3)
- Cisco — Cisco IOS XE Software (16.12.9)
- Cisco — Cisco IOS XE Software (17.11.1)
- Cisco — Cisco IOS XE Software (17.10.1b)
- Cisco — Cisco IOS XE Software (17.6.6)
- Cisco — Cisco IOS XE Software (17.9.1x1)
- Cisco — Cisco IOS XE Software (17.11.1a)
- Cisco — Cisco IOS XE Software (17.9.3a)
- Cisco — Cisco IOS XE Software (17.12.1)
- Cisco — Cisco IOS XE Software (17.3.8)
- Cisco — Cisco IOS XE Software (17.9.4)
- Cisco — Cisco IOS XE Software (16.12.10)
- Cisco — Cisco IOS XE Software (17.12.1w)
- Cisco — Cisco IOS XE Software (17.9.1y1)
- Cisco — Cisco IOS XE Software (17.12.1a)
- Cisco — Cisco IOS XE Software (17.9.5)
- Cisco — Cisco IOS XE Software (17.13.1)
- Cisco — Cisco IOS XE Software (17.12.1x)
- Cisco — Cisco IOS XE Software (17.12.2)
- Cisco — Cisco IOS XE Software (17.14.1)
- Cisco — Cisco IOS XE Software (17.9.4a)
- Cisco — Cisco IOS XE Software (17.3.8a)
- Cisco — Cisco IOS XE Software (17.6.6a)
- Cisco — Cisco IOS XE Software (17.6.5a)
- Cisco — Cisco IOS XE Software (17.6.7)
- Cisco — Cisco IOS XE Software (16.12.10a)
- Cisco — Cisco IOS XE Software (17.15.1)
- Cisco — Cisco IOS XE Software (17.13.1a)
- Cisco — Cisco IOS XE Software (17.12.2a)
- Cisco — Cisco IOS XE Software (16.12.11)
- Cisco — Cisco IOS XE Software (17.12.3)
- Cisco — Cisco IOS XE Software (17.12.1y)
- Cisco — Cisco IOS XE Software (17.12.1z)
- Cisco — Cisco IOS XE Software (17.9.5a)
- Cisco — Cisco IOS XE Software (17.14.1a)
- Cisco — Cisco IOS XE Software (17.9.5b)
- Cisco — Cisco IOS XE Software (17.6.8)
- Cisco — Cisco IOS XE Software (16.12.12)
- Cisco — Cisco IOS XE Software (17.12.4)
- Cisco — Cisco IOS XE Software (17.9.6)
- Cisco — Cisco IOS XE Software (17.17.1)
- Cisco — Cisco IOS XE Software (17.16.1)
- Cisco — Cisco IOS XE Software (17.15.1w)
- Cisco — Cisco IOS XE Software (17.12.3a)
- Cisco — Cisco IOS XE Software (17.9.5c)
- Cisco — Cisco IOS XE Software (17.15.1a)
- Cisco — Cisco IOS XE Software (17.12.1z1)
- Cisco — Cisco IOS XE Software (17.15.2)
- Cisco — Cisco IOS XE Software (17.15.1b)
- Cisco — Cisco IOS XE Software (17.9.5d)
- Cisco — Cisco IOS XE Software (17.15.1x)
- Cisco — Cisco IOS XE Software (17.9.6a)
- Cisco — Cisco IOS XE Software (17.12.1z2)
- Cisco — Cisco IOS XE Software (17.6.8a)
- Cisco — Cisco IOS XE Software (17.16.1a)
- Cisco — Cisco IOS XE Software (16.12.13)
- Cisco — Cisco IOS XE Software (17.15.3)
- Cisco — Cisco IOS XE Software (17.9.7)
- Cisco — Cisco IOS XE Software (17.12.5)
- Cisco — Cisco IOS XE Software (17.15.1y)
- Cisco — Cisco IOS XE Software (17.9.5e)
- Cisco — Cisco IOS XE Software (17.12.4a)
- Cisco — Cisco IOS XE Software (17.15.2a)
- Cisco — Cisco IOS XE Software (17.15.2c)
- Cisco — Cisco IOS XE Software (17.15.2b)
- Cisco — Cisco IOS XE Software (17.12.1z3)
- Cisco — Cisco IOS XE Software (17.9.5f)
- Cisco — Cisco IOS XE Software (17.12.4b)
- Cisco — Cisco IOS XE Software (17.12.5a)
- Cisco — Cisco IOS XE Software (17.18.1)
- Cisco — Cisco IOS XE Software (17.12.6)
- Cisco — Cisco IOS XE Software (17.12.1z4)
- Cisco — Cisco IOS XE Software (17.9.8)
- Cisco — Cisco IOS XE Software (17.9.7a)
- Cisco — Cisco IOS XE Software (17.15.3a)
- Cisco — Cisco IOS XE Software (17.15.4)
- Cisco — Cisco IOS XE Software (17.12.5b)
- Cisco — Cisco IOS XE Software (17.15.3b)
- Cisco — Cisco IOS XE Software (16.12.14)
- Cisco — Cisco IOS XE Software (17.18.1z)
- Cisco — Cisco IOS XE Software (17.9.7b)
- Cisco — Cisco IOS XE Software (17.12.5c)
- Cisco — Cisco IOS XE Software (26.1.1)
- Cisco — Cisco IOS XE Software (17.18.1a)
- Cisco — Cisco IOS XE Software (17.15.4a)
- Cisco — Cisco IOS XE Software (17.18.2)
- Cisco — Cisco IOS XE Software (17.18.1w)
- Cisco — Cisco IOS XE Software (17.15.4b)
- Cisco — Cisco IOS XE Software (17.12.6a)
- Cisco — Cisco IOS XE Software (17.12.7)
- Cisco — Cisco IOS XE Software (17.15.4c)
- Cisco — Cisco IOS XE Software (17.9.9)
- Cisco — Cisco IOS XE Software (17.12.5d)
- Cisco — Cisco IOS XE Software (16.12.15)
- Cisco — Cisco IOS XE Software (17.15.4s1)
- Cisco — Cisco IOS XE Software (17.15.5)
- Cisco — Cisco IOS XE Software (17.12.1z5)
- Cisco — Cisco IOS XE Software (17.18.1x)
- Cisco — Cisco IOS XE Software (17.12.1z6)
- Cisco — Cisco IOS XE Software (17.15.4d)
- Cisco — Cisco IOS XE Software (17.12.6b)
- Cisco — Cisco IOS XE Software (17.4.1c)
- Cisco — Cisco IOS XE Software (17.15.5a)
- Cisco — Cisco IOS XE Software (17.18.1y)
- Cisco — Cisco IOS XE Software (17.12.7a)
- Cisco — Cisco IOS XE Software (17.18.3)
- Cisco — Cisco IOS XE Software (17.12.7b)
- Cisco — Cisco IOS XE Software (17.18.3a)
- Cisco — Cisco IOS XE Software (26.1.1a)
- Cisco — Cisco IOS XE Software (17.15.7)
- Cisco — Cisco IOS XE Software (16.12.16)

## References

- [CNA](https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-hardening-iosxe-V8NMuMZJ)
- [CVE](https://www.cve.org/Media/News/item/blog/2026/06/16/Preserving-Vulnerability-Level-Identification)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.28%
- **EPSS Percentile:** 20.0

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._