CVE-2026-42086

OpenC3 COSMOS provides the functionality needed to send commands to and receive data from one or more embedded systems. Prior to version 7.0.0, the Command Sender UI uses an unsafe eval() function on array-like command parameters, which allows a user-supplied payload to execute in the browser when sending a command. This creates a self-XSS risk because an attacker can trigger their own script execution in the victim’s session, if allowed to influence the array parameter input, for example via phishing. If successful, an attacker may read or modify data in the authenticated browser context, including session tokens in local storage. This issue has been patched in version 7.0.0.

OpenC3 COSMOS provides the functionality needed to send commands to and receive data from one or more embedded systems. Prior to version 7.0.0, the Command Sender UI uses an unsafe eval() function on array-like command parameters, which allows a user-supplied payload to execute in the browser when sending a command. This creates a self-XSS risk because an attacker can trigger their own script execution in the victim’s session, if allowed to influence the array parameter input, for example via phishing. If successful, an attacker may read or modify data in the authenticated browser context, including session tokens in local storage. This issue has been patched in version 7.0.0.

Summary

The Command Sender UI uses an unsafe eval() function on array-like command parameters, which allows a user-supplied payload to execute in the browser when sending a command. This creates a self-XSS risk because an attacker can trigger their own script execution in the victim’s session, if allowed to influence the array parameter input, for example via phishing. If successful, an attacker may read or modify data in the authenticated browser context, including session tokens in local storage.

Details

The unsafe eval() usage on user-supplied ARRAY parameters happens in convertToValue method in CommandSender.vue

PoC

1. Using a drop-down form, choose any command that supports ARRAY parameters,
2. Inside square brackets “[…]” place a JavaScript code to be executed
3. Send command to CmdTlmServer using dedicated “Send” button
4. Observe JavaScript code being executed in the current browser session context

Below example uses INST ARYCMD to execute simple JavaScript code snippet alert(“XSS”). <img width="947" height="356" alt="image" src="https://github.com/user-attachments/assets/6fbdb6c9-616a-4268-bbb8-a8a1044437ad" />

<img width="942" height="545" alt="image" src="https://github.com/user-attachments/assets/4df24353-aea0-4aa0-adcf-b7c7e387dc83" />

Impact

Local JavaScript execution in the user's browser

OpenC3 COSMOS provides the functionality needed to send commands to and receive data from one or more embedded systems. Prior to version 7.0.0, the Command Sender UI uses an unsafe eval() function on array-like command parameters, which allows a user-supplied payload to execute in the browser when sending a command. This creates a self-XSS risk because an attacker can trigger their own script execution in the victim’s session, if allowed to influence the array parameter input, for example via phishing. If successful, an attacker may read or modify data in the authenticated browser context, including session tokens in local storage. This issue has been patched in version 7.0.0.

OpenC3 COSMOS provides the functionality needed to send commands to and receive data from one or more embedded systems. Prior to version 7.0.0, the Command Sender UI uses an unsafe eval() function on array-like command parameters, which allows a user-supplied payload to execute in the browser when sending a command. This creates a self-XSS risk because an attacker can trigger their own script execution in the victim’s session, if allowed to influence the array parameter input, for example via phishing. If successful, an attacker may read or modify data in the authenticated browser context, including session tokens in local storage. This issue has been patched in version 7.0.0.

Summary

The Command Sender UI uses an unsafe eval() function on array-like command parameters, which allows a user-supplied payload to execute in the browser when sending a command. This creates a self-XSS risk because an attacker can trigger their own script execution in the victim’s session, if allowed to influence the array parameter input, for example via phishing. If successful, an attacker may read or modify data in the authenticated browser context, including session tokens in local storage.

Details

The unsafe eval() usage on user-supplied ARRAY parameters happens in convertToValue method in CommandSender.vue

PoC

1. Using a drop-down form, choose any command that supports ARRAY parameters,
2. Inside square brackets “[…]” place a JavaScript code to be executed
3. Send command to CmdTlmServer using dedicated “Send” button
4. Observe JavaScript code being executed in the current browser session context

Below example uses INST ARYCMD to execute simple JavaScript code snippet alert(“XSS”). <img width="947" height="356" alt="image" src="https://github.com/user-attachments/assets/6fbdb6c9-616a-4268-bbb8-a8a1044437ad" />

<img width="942" height="545" alt="image" src="https://github.com/user-attachments/assets/4df24353-aea0-4aa0-adcf-b7c7e387dc83" />

Impact

Local JavaScript execution in the user's browser

OpenC3 COSMOS provides the functionality needed to send commands to and receive data from one or more embedded systems. Prior to version 7.0.0, the Command Sender UI uses an unsafe eval() function on array-like command parameters, which allows a user-supplied payload to execute in the browser when sending a command. This creates a self-XSS risk because an attacker can trigger their own script execution in the victim’s session, if allowed to influence the array parameter input, for example via phishing. If successful, an attacker may read or modify data in the authenticated browser context, including session tokens in local storage. This issue has been patched in version 7.0.0.