CVE-2026-20271
Modified Modified - Updated After Analysis

Insufficient Control Flow Management in Cisco IOS XE Software

Publication date: 2026-08-05

Last updated on: 2026-08-14

Assigner: Cisco Systems, Inc.

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.  

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published
2026-08-05
Last Modified
2026-08-14
Generated
2026-08-18
AI Q&A
2026-08-05
EPSS Evaluated
2026-08-17
NVD
CVE-2026-20271
EUVD
EUVD-2026-53457

Affected Vendors & Products

Showing 267 associated CPEs
Vendor Product Version / Range
cisco ios_xe 16.6.3
cisco ios_xe 16.8.1
cisco ios_xe 16.7.1
cisco ios_xe 16.6.2
cisco ios_xe 16.9.1
cisco ios_xe 16.8.1a
cisco ios_xe 16.8.1s
cisco ios_xe 16.8.1b
cisco ios_xe 16.8.2
cisco ios_xe 16.7.2
cisco ios_xe 16.8.1d
cisco ios_xe 16.7.3
cisco ios_xe 16.7.1a
cisco ios_xe 16.7.1b
cisco ios_xe 16.8.1c
cisco ios_xe 16.8.1e
cisco ios_xe 16.9.1s
cisco ios_xe 16.9.1c
cisco ios_xe 16.9.1b
cisco ios_xe 16.9.1d
cisco ios_xe 16.6.4s
cisco ios_xe 16.6.4
cisco ios_xe 16.10.1
cisco ios_xe 16.7.4
cisco ios_xe 16.9.1a
cisco ios_xe 16.9.2a
cisco ios_xe 16.9.2
cisco ios_xe 16.6.4a
cisco ios_xe 16.12.1
cisco ios_xe 16.6.5
cisco ios_xe 16.11.1
cisco ios_xe 17.1.1
cisco ios_xe 16.11.1a
cisco ios_xe 16.12.1c
cisco ios_xe 16.12.1t
cisco ios_xe 16.11.2
cisco ios_xe 16.12.1s
cisco ios_xe 16.12.1a
cisco ios_xe 16.12.1x
cisco ios_xe 16.11.1c
cisco ios_xe 16.11.1b
cisco ios_xe 16.11.1s
cisco ios_xe 16.12.1w
cisco ios_xe 16.10.1s
cisco ios_xe 16.10.1d
cisco ios_xe 16.9.2s
cisco ios_xe 16.6.6
cisco ios_xe 16.9.3h
cisco ios_xe 16.6.5b
cisco ios_xe 16.6.5a
cisco ios_xe 16.9.3a
cisco ios_xe 16.10.1a
cisco ios_xe 16.10.1f
cisco ios_xe 16.10.1g
cisco ios_xe 16.10.2
cisco ios_xe 16.9.3
cisco ios_xe 16.12.1y
cisco ios_xe 16.10.1e
cisco ios_xe 16.10.1b
cisco ios_xe 16.8.3
cisco ios_xe 16.9.3s
cisco ios_xe 16.10.1c
cisco ios_xe 16.9.4
cisco ios_xe 16.12.2
cisco ios_xe 16.6.7a
cisco ios_xe 16.9.4c
cisco ios_xe 16.12.2a
cisco ios_xe 16.6.7
cisco ios_xe 16.10.3
cisco ios_xe 16.12.4
cisco ios_xe 16.12.8
cisco ios_xe 16.9.5
cisco ios_xe 16.9.5f
cisco ios_xe 16.6.8
cisco ios_xe 16.12.3
cisco ios_xe 17.2.1
cisco ios_xe 17.4.1
cisco ios_xe 16.6.9
cisco ios_xe 17.1.1s
cisco ios_xe 16.12.2t
cisco ios_xe 17.1.1a
cisco ios_xe 16.12.2s
cisco ios_xe 16.12.3a
cisco ios_xe 17.1.1t
cisco ios_xe 17.2.1a
cisco ios_xe 17.2.1v
cisco ios_xe 16.12.1z
cisco ios_xe 16.12.3s
cisco ios_xe 17.2.1r
cisco ios_xe 17.1.2
cisco ios_xe 16.12.4a
cisco ios_xe 17.1.3
cisco ios_xe 17.2.2
cisco ios_xe 17.3.1
cisco ios_xe 17.4.1a
cisco ios_xe 17.3.2
cisco ios_xe 17.4.1b
cisco ios_xe 17.3.1a
cisco ios_xe 17.3.2a
cisco ios_xe 17.3.1w
cisco ios_xe 17.2.3
cisco ios_xe 16.9.6
cisco ios_xe 17.3.1x
cisco ios_xe 16.12.5
cisco ios_xe 16.12.5b
cisco ios_xe 16.12.1z1
cisco ios_xe 16.12.5a
cisco ios_xe 17.5.1
cisco ios_xe 16.12.1z2
cisco ios_xe 17.3.1z
cisco ios_xe 17.3.3
cisco ios_xe 17.3.3a
cisco ios_xe 17.4.1c
cisco ios_xe 16.9.7
cisco ios_xe 17.5.1a
cisco ios_xe 17.6.1
cisco ios_xe 17.3.4a
cisco ios_xe 17.4.2
cisco ios_xe 17.3.4b
cisco ios_xe 17.6.1a
cisco ios_xe 17.3.4c
cisco ios_xe 16.6.10
cisco ios_xe 17.4.2a
cisco ios_xe 16.9.8
cisco ios_xe 17.3.4
cisco ios_xe 16.12.6a
cisco ios_xe 16.12.6
cisco ios_xe 17.6.3
cisco ios_xe 17.9.1
cisco ios_xe 16.9.8a
cisco ios_xe 16.12.7
cisco ios_xe 17.3.5
cisco ios_xe 17.6.2
cisco ios_xe 17.6.3a
cisco ios_xe 17.7.1
cisco ios_xe 17.7.1a
cisco ios_xe 17.7.2
cisco ios_xe 17.8.1
cisco ios_xe 17.8.1a
cisco ios_xe 17.11.1
cisco ios_xe 17.10.1
cisco ios_xe 17.3.6
cisco ios_xe 17.3.5a
cisco ios_xe 17.3.5b
cisco ios_xe 17.6.4
cisco ios_xe 17.9.1a
cisco ios_xe 17.9.1w
cisco ios_xe 16.9.8b
cisco ios_xe 16.12.9
cisco ios_xe 17.3.7
cisco ios_xe 17.6.1x
cisco ios_xe 17.6.1z
cisco ios_xe 17.6.1z1
cisco ios_xe 17.6.5
cisco ios_xe 17.7.1b
cisco ios_xe 17.10.1a
cisco ios_xe 17.10.1b
cisco ios_xe 17.9.2
cisco ios_xe 17.9.1x
cisco ios_xe 17.9.1y
cisco ios_xe 17.9.3
cisco ios_xe 17.9.2a
cisco ios_xe 17.9.1x1
cisco ios_xe 17.9.3a
cisco ios_xe 17.9.1y1
cisco ios_xe 17.11.1a
cisco ios_xe 17.6.5a
cisco ios_xe 17.13.1a
cisco ios_xe 17.13.1
cisco ios_xe 17.12.1y
cisco ios_xe 17.12.2a
cisco ios_xe 17.12.3
cisco ios_xe 17.12.2
cisco ios_xe 17.12.1x
cisco ios_xe 17.12.1a
cisco ios_xe 17.12.1w
cisco ios_xe 17.12.1
cisco ios_xe 17.9.5b
cisco ios_xe 17.9.5a
cisco ios_xe 17.9.4a
cisco ios_xe 17.9.5
cisco ios_xe 17.9.4
cisco ios_xe 17.6.7
cisco ios_xe 17.6.6a
cisco ios_xe 17.6.6
cisco ios_xe 17.3.8a
cisco ios_xe 17.3.8
cisco ios_xe 16.12.11
cisco ios_xe 16.12.10a
cisco ios_xe 16.12.10
cisco ios_xe 17.14.1a
cisco ios_xe 17.12.4
cisco ios_xe 17.15.1a
cisco ios_xe 17.12.3a
cisco ios_xe 17.14.1
cisco ios_xe 16.12.12
cisco ios_xe 17.12.1z
cisco ios_xe 17.12.1z1
cisco ios_xe 17.12.1z2
cisco ios_xe 17.12.4a
cisco ios_xe 17.12.4b
cisco ios_xe 17.15.1
cisco ios_xe 17.15.1b
cisco ios_xe 17.15.1w
cisco ios_xe 17.15.1x
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 17.16.1
cisco ios_xe 17.16.1a
cisco ios_xe 17.6.8
cisco ios_xe 17.6.8a
cisco ios_xe 17.9.5e
cisco ios_xe 17.9.6
cisco ios_xe 17.9.6a
cisco ios_xe 17.9.5f
cisco ios_xe 17.12.1z4
cisco ios_xe 16.12.13
cisco ios_xe 17.12.1z3
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 17.15.1y
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 17.17.1
cisco ios_xe 17.9.7
cisco ios_xe 17.9.7a
cisco ios_xe 17.9.7b
cisco ios_xe 16.12.14
cisco ios_xe 16.12.15
cisco ios_xe 16.12.16
cisco ios_xe 17.12.1z5
cisco ios_xe 17.12.1z6
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 17.15.4a
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 17.18.1a
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 17.9.5c
cisco ios_xe 17.9.5d
cisco ios_xe 17.9.8
cisco ios_xe 17.9.9
cisco ios_xe 26.1.1
cisco ios_xe 26.1.1a

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-691 The code does not sufficiently manage its control flow during execution, creating conditions in which the control flow can be modified in unexpected ways.

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Executive Summary

This vulnerability is part of Cisco IOS XE Software's internal security review addressing multiple issues. It involves insufficient control flow management, categorized under CWE-691, which can lead to unexpected behavior in the software.

Detection Guidance

The provided CVE data does not include specific detection methods or commands for identifying CVE-2026-20271 on a network or system. Detection would typically involve checking the software version of Cisco IOS XE against the affected releases and applying Cisco's recommended updates.

Impact Analysis

The vulnerability may cause denial of service conditions due to high availability impact (CVSS score 8.6). It does not directly allow data access or modification but could disrupt system operations.

Compliance Impact

The provided CVE data does not specify direct impacts on compliance with standards like GDPR or HIPAA. The vulnerability involves insufficient control flow management (CWE-691) with a high CVSS score (8.6), which could potentially lead to denial-of-service conditions. However, explicit compliance implications are not detailed in the given context.

Mitigation Strategies

Apply the latest Cisco IOS XE Software updates addressing CVE-2026-20271. Monitor Cisco PSIRT advisories for patches and follow their recommended hardening steps.

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