CVE-2026-20311
Received Received - Intake

Denial of Service in Cisco IOS XE Software

Publication date: 2026-08-05

Last updated on: 2026-08-05

Assigner: Cisco Systems, Inc.

Description
A vulnerability in the web-based management interface of Cisco IOS XE Software could allow an authenticated, remote attacker with low privileges to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to insufficient error handling in the web-based management interface. An attacker could exploit this vulnerability by authenticating with a malformed certificate. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition.

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Meta Information

Published
2026-08-05
Last Modified
2026-08-05
Generated
2026-08-05
AI Q&A
2026-08-05
EPSS Evaluated
N/A
NVD
CVE-2026-20311
EUVD
EUVD-2026-53475

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
cisco ios_xe_software *

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-126 The product reads from a buffer using buffer access mechanisms such as indexes or pointers that reference memory locations after the targeted buffer.

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Executive Summary

This is a medium-severity vulnerability in Cisco IOS XE Software's web-based management interface. It allows an authenticated remote attacker with low privileges to cause a denial of service (DoS) condition on an affected device by exploiting insufficient error handling during authentication with a malformed certificate.

Detection Guidance

Check if your Cisco IOS XE device has the HTTP Server feature enabled and PIV authentication turned on. Inspect logs for malformed certificate authentication attempts or unexpected device reloads.

Impact Analysis

The vulnerability could force the affected Cisco device to reload, disrupting network services and causing downtime. It requires an attacker to have authentication privileges and the HTTP Server feature enabled with PIV authentication turned on.

Compliance Impact

This vulnerability could indirectly impact compliance with standards like GDPR or HIPAA by causing a denial of service on network devices, potentially disrupting access to critical systems or data processing environments. A DoS condition may lead to service unavailability, which could violate availability requirements in these regulations.

Mitigation Strategies

Upgrade to the fixed Cisco IOS XE Software versions provided by Cisco. Disable the HTTP Server feature if not required or turn off PIV authentication until patched.

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