CVE-2026-20270

Modified Modified - Updated After Analysis

Incorrect Calculation Issue 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-2026-20270 are related to incorrect calculation issues that are grouped under the Common Weakness Enumeration (CWE) Pillar CWE-682.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published

2026-08-05

Last Modified

2026-08-14

Generated

2026-08-16

AI Q&A

2026-08-05

EPSS Evaluated

2026-08-15

NVD

CVE-2026-20270

EUVD

EUVD-2026-53456

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-682	The product performs a calculation that generates incorrect or unintended results that are later used in security-critical decisions or resource management.

Attack-Flow Graph

Executive Summary

This vulnerability is related to incorrect calculation issues in Cisco IOS XE Software, identified under CWE-682. It was discovered during Cisco's internal security review and affects multiple products.

Detection Guidance

The provided CVE data does not include specific detection methods or commands for CVE-2026-20270. Detection would typically involve checking Cisco IOS XE Software versions against fixed releases and monitoring for unusual behavior related to incorrect calculation issues under CWE-682.

Impact Analysis

The vulnerability has a high impact on availability (A:H) with a CVSS score of 8.6. It could lead to system crashes or denial of service due to incorrect calculations in the software.

Compliance Impact

The provided CVE data does not specify direct impacts on compliance with standards like GDPR or HIPAA. The vulnerability involves incorrect calculation issues (CWE-682) in Cisco IOS XE Software, which may lead to availability impacts (CVSS 8.6). Compliance implications would depend on specific system configurations and data processing contexts.

Mitigation Strategies

Update Cisco IOS XE Software to the latest hardened release provided by Cisco to address the incorrect calculation issues. Monitor Cisco's security advisories for patches and apply them promptly.

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