Several vulnerabilities in the FreePBX platform have been disclosed and patched, including a critical authentication bypass and flaws enabling SQL injection and arbitrary file upload. Read this Cybersecurity Threat Advisory for an analysis, remediation steps, and detection guidance.
What is the threat?
Multiple security vulnerabilities critically impact the open‑source FreePBX private branch exchange (PBX) platform. The issues include:
- An AUTHTYPE‑related authentication bypass that can expose administrative functions in certain configurations.
- SQL injection vulnerabilities that allow attackers to manipulate application behavior and potentially escalate impact.
- Arbitrary file upload flaws enabling attackers to place executable code (e.g., web shells), leading to remote code execution (RCE).
Researchers have demonstrated practical exploitation paths, detailing affected components and configurations—as well as chained attacks that culminate in RCE.
Why is it noteworthy?
FreePBX is widely used for voice services, making it a high‑value target. The combination of authentication bypass, injection, and file‑upload vulnerabilities significantly increases the likelihood of real‑world exploitation, especially on systems with internet‑exposed admin interfaces. Research highlights viable attack chains and provides detection guidance, underscoring the urgency of patching and configuration hardening.
What is the exposure or risk?
Unpatched or misconfigured FreePBX systems may face unauthenticated or low‑effort compromise, potentially resulting in:
- Remote command execution on PBX hosts
- Account takeover and credential/token exposure
- Toll fraud, call manipulation, and exfiltration of call logs or recordings
- Lateral movement using the PBX as an entry point
Risk is especially high for systems with exposed admin interfaces or permissive AUTHTYPE settings.
What are the recommendations?
Barracuda recommends the following steps to secure your systems:
- Identify all FreePBX instances and review their versions, modules, and AUTHTYPE configurations.
- Apply the latest patches addressing the authentication bypass, SQL injection, and file-upload/RCE vulnerabilities. Validate patching and test critical call flows afterward.
- Restrict access to admin interfaces, enforce strong authentication, and adjust AUTHTYPE settings to avoid insecure configurations.
- Monitor logs for suspicious uploads, unexpected admin activity, and SQL injection patterns. Use WAF/IPS rules aligned with known indicators and published detection guidance.
- If compromise is suspected, isolate affected systems, rotate credentials and tokens, verify the integrity of recordings and configurations, and inspect for persistence mechanisms such as web shells or altered modules.
References
For more in-depth information about the recommendations, please visit the following links:
- https://thehackernews.com/2025/12/freepbx-authentication-bypass-exposed.html
- https://github.com/FreePBX/security-reporting/security/advisories/GHSA-9jvh-mv6x-w698
- http://github.com/FreePBX/security-reporting/security/advisories/GHSA-7p8x-8m3m-58j9
- https://github.com/FreePBX/security-reporting/security/advisories/GHSA-292p-rj6h-54cp
- https://horizon3.ai/attack-research/the-freepbx-rabbit-hole-cve-2025-66039-and-others/
- https://www.cypro.se/2025/12/15/freepbx-patches-critical-sqli-file-upload-and-authtype-bypass-flaws-enabling-rce/
If you have any questions about this Cybersecurity Threat Advisory, don’t hesitate to get in touch with Barracuda Managed XDR’s Security Operations Center.
This post originally appeared on Smarter MSP.