CVE-2026-20308 in IOS XE Software
Summary
by MITRE • 08/05/2026
A vulnerability in the web-based management interface of Cisco IOS XE Software could allow an authenticated, remote attacker with low privileges to perform a denial of service (DoS) attack against an affected device.
This vulnerability is due to insufficient input validation. An attacker could exploit this vulnerability by sending crafted input to the web-based management interface of an affected device. A successful exploit could allow the attacker to cause the web-based management interface to become unresponsive.
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Analysis
by VulDB Data Team • 08/05/2026
This vulnerability resides within Cisco IOS XE Software's web-based management interface, representing a critical security gap that enables authenticated remote attackers with minimal privileges to execute denial of service attacks against network devices. The flaw stems from inadequate input validation mechanisms that fail to properly sanitize or validate user-provided data before processing. Attackers can exploit this weakness by crafting malicious inputs specifically designed to trigger unexpected behavior in the web interface, ultimately leading to service disruption and device unresponsiveness.
The technical exploitation of this vulnerability follows a classic pattern of insufficient input validation as classified under CWE-20, which encompasses weaknesses related to improper handling of input data. When an authenticated user submits crafted payloads through the web interface, the system fails to properly validate or filter these inputs before processing them, creating opportunities for attackers to manipulate the application's normal operation flow. The vulnerability manifests as a denial of service condition where the web management interface becomes unresponsive, effectively preventing legitimate administrators from accessing critical device configuration and monitoring functions.
From an operational impact perspective, this vulnerability presents significant risks to network infrastructure availability and management capabilities. Network administrators rely heavily on web-based interfaces for routine maintenance, configuration changes, and real-time monitoring of their devices. When the interface becomes unresponsive due to exploitation, it creates immediate service disruption that can cascade into broader network management issues, potentially affecting business continuity and operational efficiency. The low privilege requirement for exploitation makes this vulnerability particularly concerning as it could be leveraged by attackers with minimal access credentials.
The attack vector operates through authenticated remote access, meaning that an attacker must first obtain valid login credentials to the device, but once authenticated, they can leverage this vulnerability to cause service disruption. This aligns with ATT&CK technique T1499.004 which covers network denial of service attacks and demonstrates how attackers can exploit software weaknesses to disrupt services without requiring physical access or elevated privileges beyond basic authentication. The vulnerability's impact extends beyond simple service interruption as it directly compromises the availability of critical management functions that organizations depend upon for device maintenance and security monitoring.
Organizations should implement immediate mitigations including applying available Cisco security patches and updates, implementing network segmentation to limit access to management interfaces, and establishing robust monitoring for unusual activity patterns in web interface access logs. The vulnerability underscores the importance of input validation as a fundamental security control, emphasizing that proper sanitization and validation of all user inputs remains critical in preventing exploitation of similar weaknesses across various application types and platforms.