CVE-2026-20271: Cisco IOS XE Software Security Hardening Release

Published Aug 5, 2026
·
Updated

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 Software

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

Event History

Aug 5, 2026
CVE Published
via MITRE·04:19 PM
Data Sourced
via MITRE·04:19 PM
DescriptionSeverityWeakness
Data Sourced
via NVD·05:16 PM
DescriptionSeverityWeaknessAffected Software

Frequently Asked Questions

1

What is the severity of CVE-2026-20271?

The severity of CVE-2026-20271 is classified as high with a score of 8.6.

2

How do I fix CVE-2026-20271?

To fix CVE-2026-20271, update your Cisco IOS XE Software to the latest hardening release provided by Cisco.

3

What systems are affected by CVE-2026-20271?

CVE-2026-20271 affects Cisco IOS XE Software installations that have not been updated with the latest security hardening release.

4

What are the potential impacts of CVE-2026-20271?

The potential impacts of CVE-2026-20271 include decreased security posture and increased risk of exploitation in vulnerable systems.

5

When was CVE-2026-20271 published?

CVE-2026-20271 was published on August 5, 2026.

Company

Resources

Contact

SecAlerts Pty Ltd.
132 Wickham Terrace
Fortitude Valley,
QLD 4006, Australia
info@secalerts.co
By using SecAlerts services, you agree to our services end-user license agreement. This website is safeguarded by reCAPTCHA and governed by the Google Privacy Policy and Terms of Service. All names, logos, and brands of products are owned by their respective owners, and any usage of these names, logos, and brands for identification purposes only does not imply endorsement. If you possess any content that requires removal, please get in touch with us.
© 2026 SecAlerts Pty Ltd.
ABN: 70 645 966 203, ACN: 645 966 203