OPNsense is a FreeBSD based firewall and routing platform. Prior to 26.1.4, multiple OPNsense MVC API endpoints perform state‑changing operations but are accessible via HTTP GET requests without CSRF protection. The framework CSRF validation in ApiControllerBase only applies to POST/PUT/DELETE methods, allowing authenticated GET requests to bypass CSRF verification.
As a result, a malicious website can trigger privileged backend actions when visited by an authenticated user, causing unintended service reloads and configuration changes through configd. This results in an authenticated Cross‑Site Request Forgery vulnerability allowing unauthorized system state changes. This vulnerability is fixed in 26.1.4.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
Low
Basic privileges needed
User Interaction
Required
User action required
Impact Assessment
Confidentiality
None
No data leak
Integrity
High
Complete data modification
Availability
Low
Partial disruption
CVSS Vector v3.1