A critical security vulnerability has been identified in Cisco’s IOS XE Wireless Controller Software, posing a significant threat to enterprise networks. Security researchers have released proof-of-concept (PoC) exploit code demonstrating how attackers can achieve remote code execution with root privileges. This vulnerability, designated as CVE-2025-20188, has been assigned the highest possible CVSS score of 10.0, underscoring its severe impact on affected systems.
Vulnerability Overview
Cisco disclosed this vulnerability on May 7, 2025, noting that it affects multiple enterprise-grade wireless controller products, including:
– Catalyst 9800-CL Wireless Controllers for Cloud
– Catalyst 9800 Embedded Wireless Controllers for Catalyst 9300/9400/9500 Series Switches
– Catalyst 9800 Series Wireless Controllers
– Embedded Wireless Controller on Catalyst Access Points (APs)
The flaw originates from a hard-coded JSON Web Token (JWT) present in the Out-of-Band Access Point (AP) Image Download feature. This vulnerability allows unauthenticated remote attackers to bypass authentication mechanisms and upload arbitrary files to vulnerable systems.
Technical Details
Security researchers at Horizon3.ai conducted an in-depth analysis by comparing vulnerable and patched firmware images. They discovered that the root cause lies within the Lua scripting components of the OpenResty web platform. Specifically, the vulnerability is found in the `ewlc_jwt_verify.lua` and `ewlc_jwt_upload_files.lua` scripts located in `/var/scripts/lua/features/`, which handle JWT verification and file upload operations, respectively.
The authentication bypass occurs when the JWT verification script reads a secret key from `/tmp/nginx_jwt_key`. If this file is missing, the system defaults to using a hard-coded value of notfound as the secret. This design flaw allows attackers to craft valid JWTs using the known secret, effectively bypassing security controls entirely.
The vulnerable endpoints include `/aparchive/upload` and `/ap_spec_rec/upload/`, configured in the nginx configuration file `/usr/binos/conf/nginx-conf/https-only/ap-conf/ewlc_auth_jwt.conf`. These endpoints process file uploads with client body sizes up to 1536MB and 500MB, respectively, providing ample opportunity for malicious payload delivery.
Proof-of-Concept Exploit
The released PoC demonstrates how attackers can leverage path traversal techniques to place files in arbitrary locations on the target system. Researchers successfully uploaded files using the filename parameter `../../usr/binos/openresty/nginx/html/foo.txt`, effectively bypassing directory restrictions through relative path manipulation.
To achieve remote code execution, attackers can exploit the internal process management service (`pvp.sh`) that monitors file changes using `inotifywait`. By overwriting configuration files and uploading trigger files, attackers can cause service reloads that execute arbitrary commands with root privileges. The researchers demonstrated this technique by modifying service configuration files and successfully extracting the `/etc/passwd` file, confirming complete system compromise.
Risk Factors
– Affected Products:
– Catalyst 9800-CL Wireless Controllers for Cloud
– Catalyst 9800 Embedded Wireless Controllers for Catalyst 9300/9400/9500 Series Switches
– Catalyst 9800 Series Wireless Controllers
– Embedded Wireless Controller on Catalyst APs
– Impact: Remote code execution with root privileges
– Exploit Prerequisites:
1. Out-of-Band AP Image Download feature enabled
2. Attacker sends crafted HTTPS requests to `/aparchive/upload` or `/ap_spec_rec/upload/` endpoints
3. Use of hard-coded JWT secret notfound for authentication bypass
– CVSS 3.1 Score: 10.0 (Critical)
Mitigation Measures
Cisco has released software updates to address this vulnerability. Administrators are strongly advised to apply these updates promptly to mitigate the risk. Additionally, it is recommended to disable the Out-of-Band AP Image Download feature if it is not required, as this can reduce the attack surface.
Conclusion
The discovery of CVE-2025-20188 highlights the critical importance of securing network infrastructure against emerging threats. Organizations utilizing affected Cisco products should take immediate action to apply the necessary patches and review their security configurations to prevent potential exploitation.
