CVE-2026-20273

Analyzed Analyzed - Analysis Complete

Improper Input Validation in Cisco IOS XE Software

Publication date: 2026-08-05

Last updated on: 2026-08-17

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 a software hardening release that addresses multiple internally discovered vulnerabilities. The vulnerabilities tracked by CVE-2026-20273 are related to improper input validation issues that are grouped under the Common Weakness Enumeration (CWE) Pillar CWE-20.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published

2026-08-05

Last Modified

2026-08-17

Generated

2026-08-26

AI Q&A

2026-08-05

EPSS Evaluated

2026-08-24

NVD

CVE-2026-20273

EUVD

EUVD-2026-53459

Affected Vendors & Products

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

KEV

CWE ID	Description
CWE-20	The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

Attack-Flow Graph

Executive Summary

This vulnerability is related to improper input validation in Cisco IOS XE Software, classified under CWE-20. It was discovered during Cisco's internal security review and affects multiple products. The issue could allow unauthorized actions due to insufficient validation of user-supplied input.

Detection Guidance

This CVE involves improper input validation in Cisco IOS XE Software. Detection typically requires reviewing system logs for unusual input patterns or crashes. No specific commands are provided in the CVE details. Check Cisco's official advisories for recommended scanning tools or CLI commands.

Impact Analysis

The vulnerability could lead to denial-of-service conditions as indicated by the CVSS score (A:H). Attackers might exploit it to cause system crashes or instability by sending specially crafted input, though it does not directly expose confidential data or allow code execution.

Compliance Impact

The vulnerability involves improper input validation, which could lead to denial-of-service conditions. This may impact compliance by disrupting data availability, a key requirement under standards like GDPR and HIPAA.

Mitigation Strategies

Update Cisco IOS XE Software to the latest version provided by Cisco to address the improper input validation issues. Monitor Cisco's security advisories for patches and apply them promptly.

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