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A Hard-Coded JWT Threat With a Perfect CVSS Score
Cisco has recently addressed a critical security flaw in its IOS XE Software used in Wireless LAN Controllers—a flaw so severe that it earned a maximum CVSS score of 10.0. Tracked as CVE-2025-20188, this vulnerability stems from a hard-coded JSON Web Token (JWT) embedded in the software, which an unauthenticated attacker can leverage to gain root-level control of affected devices remotely. This alarming issue is tied specifically to the ‘Out-of-Band AP Image Download’ feature, which, though disabled by default, may be active in large-scale enterprise environments where automated provisioning is common.
The embedded JWT allows attackers to pose as authorized users without providing actual credentials, potentially enabling them to perform full system compromises. Cisco has since released patches to resolve the flaw and is urging administrators to implement them immediately, especially in environments where the feature is enabled.
CVE-2025-20188 Explained in
Cisco identified a critical vulnerability in its IOS XE Software for Wireless LAN Controllers.
The flaw is due to a hard-coded JSON Web Token (JWT) used in authentication.
JWTs are normally unique and secured, but this one was hard-coded, making it universally exploitable.
Attackers can send specially crafted HTTPS requests to exploit the vulnerability.
Once exploited, attackers can:
Upload arbitrary files,
Perform path traversal,
Execute commands with root privileges.
The flaw affects the ‘Out-of-Band AP Image Download’ feature.
This feature is disabled by default, but can be turned on in enterprise deployments.
It allows Access Points (APs) to download firmware over HTTPS.
This method offers flexibility compared to traditional CAPWAP-based firmware delivery.
If enabled, the flaw provides attackers a gateway to critical system functions.
Affected device models include:
Catalyst 9800-CL for Cloud,
Catalyst 9800 Embedded Controllers for 9300/9400/9500 Switches,
Catalyst 9800 Series Wireless Controllers,
Embedded WLCs on Catalyst APs.
Devices not affected include:
Cisco IOS (non-XE),
Cisco IOS XR,
Cisco Meraki products,
Cisco NX-OS,
Cisco AireOS-based WLCs.
Cisco issued security patches addressing this vulnerability.
There are no current workarounds beyond disabling the affected feature.
Disabling the ‘Out-of-Band AP Image Download’ is an effective temporary safeguard.
Cisco’s advisory notes no current evidence of active exploitation.
However, given its critical nature, threat actors are expected to begin scans soon.
System administrators are urged to:
Check device configurations,
Disable the risky feature if unused,
Apply the official updates immediately.
Cisco provides a Software Checker Tool to verify vulnerability status per model.
The exploit’s ease of use—no credentials required—amplifies its danger.
Its CVSS score of 10.0 reflects complete system compromise potential.
This flaw highlights broader risks in using static or hard-coded credentials in firmware.
Enterprises prioritizing rapid AP provisioning are particularly at risk.
Once exploited, attackers can establish long-term control over networks.
The vulnerability underscores the importance of secure software development practices.
Organizations should audit all enabled features in their network devices.
Monitoring for unusual AP download traffic may help detect exploit attempts.
Updating firmware and disabling unused features are key defenses.
What Undercode Say:
Cisco’s CVE-2025-20188 vulnerability spotlights one of the most glaring software design oversights: the use of hard-coded credentials—in this case, a JSON Web Token (JWT). What should serve as a unique, secure mechanism for access control instead becomes a skeleton key for attackers when left static and embedded. Despite the feature being off by default, large enterprise environments with automated provisioning routines may unknowingly open a severe backdoor.
Let’s dissect why this vulnerability is so critical. JWTs are often used in modern web services for secure API authentication. By hard-coding one, Cisco essentially handed attackers a passport valid across all enabled devices. That’s akin to printing a master admin password in plain text into every unit shipped.
The attack vector is also concerning: HTTPS requests. This means the attack can occur over encrypted channels, possibly evading basic intrusion detection systems. And since it grants root privileges, the attacker doesn’t just peek into the system—they own it.
From a threat landscape perspective, while no exploitation has been reported yet, vulnerabilities like these rarely remain dormant for long. CVSS 10.0 flaws attract threat actors like bees to honey. We’ve seen it repeatedly in the past: once publicly disclosed, such bugs get rapidly integrated into automated scanning tools and malware kits. The longer the patch delay, the greater the risk.
Enterprise environments that leverage the ‘Out-of-Band AP Image Download’ feature for convenience now face a trade-off between ease and exposure. For many, disabling the feature is the fastest route to mitigation, even if it slightly slows deployment times. However, this also calls for a deeper introspection about network hygiene—how many features are enabled unnecessarily and left unsupervised?
Cisco’s quick response deserves praise, especially for issuing targeted patches and providing tools like the Software Checker. Still, the underlying problem—embedding static tokens—raises questions about their internal security review processes. In an age where zero-trust architectures are championed, this kind of vulnerability feels especially anachronistic.
Organizations should not treat this as a one-off patch job. Instead, this is a wake-up call to reassess device configurations, tighten firmware deployment policies, and apply least-privilege principles rigorously. Regular auditing, proper segmentation of wireless controllers, and anomaly detection around firmware downloads should now be part of every serious security strategy.
As this incident illustrates, even a single line of insecure code can undermine entire network ecosystems.
Fact Checker Results:
Cisco has officially acknowledged CVE-2025-20188 and released security patches.
The vulnerability stems from a hard-coded JWT used in a non-default feature.
No exploitation in the wild has been reported at the time of disclosure.
Prediction:
Given the flaw’s CVSS 10.0 rating and simplicity of exploitation, we expect rapid adoption of this exploit by opportunistic threat actors and inclusion in automated vulnerability scanners. Within weeks, unpatched systems with the ‘Out-of-Band AP Image Download’ feature enabled are likely to become primary targets for botnet recruitment and network intrusions. Enterprises that delay patching or leave default configurations unchecked may face severe breaches in the near future.
References:
Reported By: www.bleepingcomputer.com
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