Description

Multiple security vulnerabilities have been identified in the open-source PBX platform FreePBX, posing serious risks to organizations relying on it for telephony services. Discovered by Horizon3.ai and disclosed in September 2025, these flaws include authenticated SQL injection, arbitrary file upload, and a critical authentication bypass issue. Under certain configurations, attackers could bypass login controls, upload malicious PHP web shells, and execute arbitrary commands, potentially leading to full system compromise. While the authentication bypass is not exploitable in FreePBX’s default configuration, misconfigured environments significantly increase exposure. The root cause of these issues lies in insecure input handling, legacy authentication logic, and risky configuration options. The SQL injection vulnerabilities allow attackers with valid access to manipulate the backend database, while the file upload flaw enables remote code execution through malicious firmware uploads. The most severe issue, CVE-2025-66039, arises when the Authorization Type (AUTHTYPE) is set to “webserver,” allowing attackers to forge authorization headers and gain administrative access. This highlights how optional but poorly secured legacy features can undermine otherwise secure systems. Organizations should immediately upgrade to patched FreePBX versions and review their configurations to ensure secure authentication settings are enforced. Administrators are strongly advised to avoid the “webserver” authentication type, limit administrative exposure, and monitor systems for signs of compromise. Additional safeguards such as network segmentation, regular audits, and strict access controls can significantly reduce risk. Given FreePBX’s widespread use in business communications, timely remediation is critical to prevent exploitation.