Critical FreePBX Vulnerabilities Expose Authentication Bypass and Remote Code Execution Risks

Researchers at Horizon3.ai have uncovered several security vulnerabilities within FreePBX, an open-source private branch exchange platform. Among them, one severity flaw could be exploited to bypass authentication if very specific configurations are enabled. The issues were disclosed privately to FreePBX maintainers in mid-September 2025, and the researchers have raised concerns about the exposure of internet-facing PBX deployments.  

According to Horizon3.ai’s analysis, the disclosed vulnerabilities affect several FreePBX core components and can be exploited by an attacker to achieve unauthorized access, manipulate databases, upload malicious files, and ultimately execute arbitrary commands. One of the most critical finding involves an authentication bypass weakness that could grant attackers access to the FreePBX Administrator Control Panel without needing valid credentials, given specific conditions. This vulnerability manifests itself in situations where the system’s authorization mechanism is configured to trust the web server rather than FreePBX’s own user management. 

Although the authentication bypass is not active in the default FreePBX configuration, it becomes exploitable with the addition of multiple advanced settings enabled. Once these are in place, an attacker can create HTTP requests that contain forged authorization headers as a way to provide administrative access. Researchers pointed out that such access can be used to add malicious users to internal database tables effectively to maintain control

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