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FreePBX, the open-source IP PBX platform, has patched several critical vulnerabilities in its Endpoint Manager module that could allow attackers to bypass authentication and achieve remote code execution. Researchers from Horizon3.ai identified three high-severity flaws: CVE-2025-66039 (authentication bypass via forged Basic Auth headers when 'webserver' authorization is enabled), CVE-2025-61675 (multiple SQL injection vulnerabilities across several endpoints), and CVE-2025-61678 (arbitrary file upload enabling PHP webshell deployment). These vulnerabilities, when chained, allow unauthenticated attackers to gain full control over affected FreePBX instances, posing a significant risk to business communications infrastructure.
The authentication bypass is not present in the default configuration but becomes exploitable if certain advanced settings are enabled. Attackers can exploit these flaws to access protected endpoints, manipulate the underlying SQL database, and upload malicious files for command execution. The vulnerabilities were responsibly disclosed to FreePBX maintainers, and patches have been released. Organizations using FreePBX, especially those with non-default authentication settings, are urged to update immediately to mitigate the risk of compromise.
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3 events from the most recent confirmed update back to the earliest known activity.
FreePBX advised administrators to use 'usermanager' authentication, disable override of readonly settings, reboot after changes, and treat 'webserver' authentication as insecure. The company also urged users who had enabled the vulnerable 'webserver' AUTHTYPE to audit systems for signs of compromise.
FreePBX released fixes for the disclosed vulnerabilities in supported branches, including versions 16.0.92/17.0.6 and 16.0.44/17.0.23. As part of the mitigation, the authentication provider selection was removed from the UI and administrators were directed to use safer configuration methods.
Horizon3.ai identified three critical vulnerabilities in FreePBX's Endpoint Manager module: an authentication bypass (CVE-2025-66039), a SQL injection flaw (CVE-2025-61675), and an arbitrary file upload flaw (CVE-2025-61678). The issues could be chained or abused to achieve unauthenticated remote code execution, especially in vulnerable configurations.
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Attackers have been exploiting **CVE-2025-64328**, a post-authentication command injection flaw in the *Sangoma FreePBX Endpoint Manager* (filestore component) to compromise internet-exposed FreePBX systems and deploy persistent web shells. The vulnerability affects FreePBX versions `17.0.2.36` and above prior to `17.0.3`, and can be abused by an authenticated user via the `testconnection -> check_ssh_connect()` function to execute commands and gain remote access as the `asterisk` user; the issue is fixed in **17.0.3**. Reporting indicates the activity began in **December 2025** and has left hundreds of systems persistently backdoored with web shells. The **Shadowserver Foundation** reported roughly **900** FreePBX instances still compromised, with the largest concentration in the **United States** (about **400**) and additional impacted systems across **Brazil, Canada, Germany, France, the UK, Italy, and the Netherlands**. Fortinet/FortiGuard Labs identified a PHP web shell dubbed **EncystPHP** associated with the campaign, which supports remote command execution, persistence, and additional web shell deployment; follow-on risk includes VoIP-focused abuse such as **outbound call fraud** and potential network pivoting from the PBX host. One source also states the vulnerability has been added to **CISA’s Known Exploited Vulnerabilities (KEV) Catalog**, reinforcing the need for rapid patching and incident response on exposed FreePBX deployments.
Jun 29, 2026
Rapid7 released new *Metasploit Framework* content adding multiple modules that weaponize a **FreePBX** vulnerability chain starting with **CVE-2025-66039** (authentication bypass) to enable unauthenticated attackers to reach **remote code execution (RCE)**. The modules, authored by **Noah King** and **msutovsky-r7**, demonstrate how an initial auth bypass can be combined with follow-on flaws to move from external access to full system compromise. The new FreePBX modules include an exploit that chains **CVE-2025-66039** with **CVE-2025-61675** (SQL injection) to insert a malicious job into the `cron_job` database table and execute arbitrary code, plus an auxiliary module using the same SQLi path to create a rogue administrator account. A second exploit chains **CVE-2025-66039** with **CVE-2025-61678** (unrestricted firmware file upload) to place a webshell on the server for RCE. Separate reporting also notes the same Metasploit update introduced additional exploit modules affecting other enterprise software (including *Cacti* and *SmarterMail*), but the detailed technical coverage in the sources focuses primarily on the FreePBX chaining approach and module implementations (e.g., `unix/http/freepbx_custom_extension_rce` and `unix/http/freepbx_firmware_file_upload`).
Jun 29, 2026
Reporting highlights two separate developments: growing criminal adoption of **Vshell**, a Go-based command-and-control framework originally promoted in Chinese-speaking offensive security communities as a lower-cost alternative to *Cobalt Strike*. Research cited in the reporting describes Vshell’s evolution from a basic RAT into a more capable post-compromise platform supporting Windows and Linux administration, traffic tunneling/relay, pivoting, and lateral movement; internet scanning also identified exposed Vshell management panels with large numbers of connected agents (e.g., a recovered panel showing **286 active clients**), indicating real-world operational use. Separately, the **Shadowserver Foundation** reported that **900+ Sangoma FreePBX** instances remain infected with web shells following exploitation of **CVE-2025-64328** (CVSS 8.6), a post-authentication command-injection flaw affecting FreePBX versions `>= 17.0.2.36` and fixed in `17.0.3`. The issue has been added to **CISA’s KEV** catalog amid active exploitation, and Fortinet linked exploitation beginning in December 2025 to the **INJ3CTOR3** cyber-fraud operation delivering an `EncystPHP` web shell; recommended mitigations include restricting access to the FreePBX Admin Control Panel (ACP) and updating affected components (including the *filestore* module).
Jun 29, 2026