OPNsense Reflected Cross-Site Scripting Vulnerability in System Advanced Sysctl Endpoint

A reflected cross-site scripting vulnerability has been identified in OPNsense version 19.1, specifically within the system_advanced_sysctl.php endpoint. This vulnerability allows attackers to inject malicious scripts via the value parameter, which are then executed as JavaScript in the context of authenticated user sessions. The issue arises from improper sanitization of user input, enabling the injection of script payloads through crafted POST requests.

Impact

Exploitation of this vulnerability allows for reflected cross-site scripting, where injected scripts are executed in the context of the user's session.

Reproduction

To reproduce this vulnerability, send a POST request to the system_advanced_sysctl.php endpoint with a script payload in the value parameter. The injected script will be executed as JavaScript in the context of the authenticated user.

Remediation

Users are advised to update to OPNsense version 19.1.1, which addresses this cross-site scripting vulnerability.