CVE-2026-30868 in core
Summary
by MITRE • 03/11/2026
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.
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Analysis
by VulDB Data Team • 03/18/2026
The vulnerability identified as CVE-2026-30868 affects OPNsense, a FreeBSD-based firewall and routing platform that serves as a critical network security component for many organizations. This issue represents a significant authenticated cross-site request forgery vulnerability that stems from improper implementation of CSRF protection mechanisms within the platform's MVC API framework. The vulnerability specifically impacts versions prior to 26.1.4, where the security controls fail to adequately protect state-changing operations that should require proper authentication and validation before execution.
The technical flaw resides in the ApplicationControllerBase class which implements CSRF validation but only applies this protection to POST, PUT, and DELETE HTTP methods. This selective implementation creates a dangerous gap in the security model where GET requests that perform state-changing operations remain unprotected against CSRF attacks. The fundamental issue occurs because authenticated users can be tricked into visiting malicious websites that contain embedded requests to the OPNsense API endpoints, causing unintended operations to execute with the privileges of the authenticated user. This design flaw directly violates security principles outlined in CWE-352, which defines cross-site request forgery vulnerabilities as those that allow attackers to perform actions on behalf of authenticated users without their knowledge or consent.
The operational impact of this vulnerability is particularly severe given that OPNsense serves as a network infrastructure component that controls firewall rules, routing configurations, and other critical system settings. When exploited, the vulnerability allows attackers to trigger privileged backend actions through configd, potentially causing unauthorized service reloads, configuration modifications, and other system state changes that could compromise network security. The authenticated nature of the attack means that the malicious website must be visited by a legitimate user who is already logged into the OPNsense interface, making the attack vector more insidious as it leverages existing trust relationships rather than requiring additional authentication bypass techniques. This vulnerability aligns with ATT&CK technique T1566.002 which describes social engineering attacks using malicious websites to execute unauthorized commands.
The mitigation strategy involves upgrading to OPNsense version 26.1.4 or later, which implements proper CSRF protection across all HTTP methods including GET requests that perform state-changing operations. Organizations should also conduct thorough security assessments of their OPNsense deployments to identify any other potential endpoints that may be similarly vulnerable. Network administrators should consider implementing additional monitoring for unauthorized configuration changes and service reloads, as these activities could serve as indicators of exploitation attempts. The fix addresses the root cause by ensuring that all API endpoints requiring authentication for state-changing operations properly validate CSRF tokens regardless of the HTTP method used, thereby closing the gap that attackers could exploit to perform unauthorized administrative actions on behalf of authenticated users.