Critical Cisco IOS XE Flaw Grants Attackers Full Control Over Wireless Controllers

A newly disclosed critical vulnerability in Cisco’s IOS XE Wireless LAN Controllers (WLCs) has sent shockwaves through the cybersecurity community, threatening the security of enterprise wireless networks worldwide.

Tracked as CVE-2025-20188, this flaw carries the highest possible severity rating-CVSS 10.0 allows unauthenticated, remote attackers to gain full control of affected devices by exploiting a hard-coded authentication token.

Technical Details: Hard-Coded JWT Enables Remote Root Access

At the heart of the vulnerability is the Out-of-Band Access Point (AP) Image Download feature, present in several Cisco IOS XE WLC products.

The flaw arises from the presence of a hard-coded JSON Web Token (JWT) on affected systems. Attackers can exploit this by sending specially crafted HTTPS requests to the AP image download interface, bypassing authentication entirely.

Upon successful exploitation, an attacker can:

• Upload arbitrary files to the device
• Perform directory traversal (path traversal)
• Execute commands with root privileges, effectively seizing total control

The vulnerability is classified under CWE-798: Use of Hard-coded Credentials.

Affected Products and Detection

The following Cisco products are vulnerable if running susceptible IOS XE releases with the Out-of-Band AP Image Download feature enabled:

• Catalyst 9800-CL Wireless Controllers for Cloud
• Catalyst 9800 Embedded Wireless Controller for Catalyst 9300, 9400, and 9500 Series Switches
• Catalyst 9800 Series Wireless Controllers
• Embedded Wireless Controller on Catalyst APs

Detection Command:
Administrators can check if their device is affected by running:

textshow running-config | include ap upgrade

If the output shows ap upgrade method https, the vulnerable feature is enabled.

Severity and Exploitation Risk

The vulnerability’s CVSS vector is AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H, indicating:

• Attack Vector (AV): Network
• Attack Complexity (AC): Low
• Privileges Required (PR): None
• User Interaction (UI): None
• Scope (S): Changed
• Confidentiality/Integrity/Availability (C/I/A): High

This means exploitation can be performed remotely, without authentication or user interaction, and results in a complete compromise of the device.

Mitigation and Remediation

No workarounds are available to fully mitigate the vulnerability without a software update.

Cisco has released free software updates to address the issue, and customers are strongly urged to upgrade immediately.

As a temporary measure, administrators can disable the Out-of-Band AP Image Download feature, which will force AP image updates to use the CAPWAP method instead-this does not affect the AP client state.

Discovery and Impact

The vulnerability was discovered internally by X.B. of the Cisco Advanced Security Initiatives Group (ASIG) during routine security testing.

Cisco’s Product Security Incident Response Team (PSIRT) has found no evidence of active exploitation in the wild as of the advisory’s publication.

Given the ease of exploitation, lack of authentication, and root-level access granted by CVE-2025-20188, this vulnerability poses a significant risk to organizations relying on Cisco wireless infrastructure.

Immediate action-either by patching or disabling the vulnerable feature-is essential to protect enterprise networks from potential compromise.

For further details and software updates, Cisco customers should consult the official security advisory and use the Cisco Software Checker to verify their exposure.

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