Cisco Security Alert: Cisco IOS XE users Urged to Patch Critical Security Flaw

A critical security vulnerability, identified as CVE-2025-20188 and rated with a maximum CVSS score of 10.0, has been discovered in the Cisco IOS XE Wireless Controller. This flaw allows unauthenticatedremote attackers to upload arbitrary files to affected systems.

Cisco IOS XE is a modern, modular, Linux-based operating system designed for Cisco networking devices like routers and switches. It supports high availability, enhanced security, programmability through APIs, and advanced features such as automation, virtualization, and application hosting, making it suitable for enterprise and service provider environments.

To understand how this vulnerability can be exploited, it’s essential to first examine its underlying cause. The root of the problem lies in the inclusion of a hardcoded JSON Web Token (JWT). Best practices dictate that JWTs should be generated dynamically for each session; failure to do so results in tokens that never expire, allowing unauthorized access to persist for extended periods. Now that we’ve clarified the cause, let’s look at how the exploitation unfolds:

• The attacker acquires the hardcoded JWT—commonly through leaked firmware, access to source code, or by reverse engineering the system.
• Using the JWT, the attacker constructs specially crafted HTTPS requests directed at the AP image download interface on the vulnerable Cisco IOS XE system.
• The static JWT allows the attacker to impersonate a trusted internal component, bypassing authentication checks without needing valid credentials.
• With elevated access, the attacker can upload arbitrary files, abuse path traversal, and execute commands as root, potentially taking full control of the device.

To verify that the exploit was successful, the attacker may check for the presence of the uploaded file or execute commands to confirm root-level privileges.

The impact of this vulnerability is severe as successful exploitation allows an attacker to upload arbitrary files, perform path traversal, and execute commands with root privileges. This can lead to complete system compromise as the attacker completely takes over the system.

This vulnerability impacts the following Cisco products when running a vulnerable version of Cisco IOS XE Software for WLCs with the Out-of-Band AP Image Download feature enabled:

• Catalyst 9800-CL Wireless Controllers deployed in cloud environments
• Catalyst 9800 Embedded Wireless Controllers integrated with Catalyst 9300, 9400, and 9500 Series Switches
• Catalyst 9800 Series Standalone Wireless Controllers
• Embedded Wireless Controllers operating on Catalyst Access Points

To determine whether a device is configured with the Out-of-Band AP Image Download feature enabled, use the show running-config | include ap upgrade command. If the command returns ap upgrade method https, the feature is enabled, and the device is affected by this vulnerability.

To determine whether a device is configured with the Out-of-Band AP Image Download feature enabled, use the show running-config | include ap upgrade command. If the command returns ap upgrade method https, the feature is enabled, and the device is affected by this vulnerability.

Update Cisco IOS XE with patches as mentioned by the vendor in the advisory.

If updating the product is not feasible, administrators are advised to disable the Out-of-Band AP Image Download feature. When this feature is disabled, Access Point image updates will revert to using the CAPWAP method, which does not affect the AP client state.

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