CVE-2025-55739 in FreePBX
Summary
by MITRE • 09/05/2025
api is a module for FreePBX@, which is an open source GUI that controls and manages Asterisk© (PBX). In versions lower than 15.0.13, 16.0.2 through 16.0.14, 17.0.1 and 17.0.2, there is an identical OAuth private key used across multiple systems that installed the same FreePBX RPM or DEB package. An attacker with access to the shared OAuth private key could forge JWT tokens, bypass authentication, and potentially gain full access to both REST and GraphQL APIs. Systems with the "api" module enabled, configured and previously activated by an administrator for remote inbound connections may be affected. This issue is fixed in versions 15.0.13, 16.0.15 and 17.0.3.
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Analysis
by VulDB Data Team • 09/05/2025
The vulnerability identified as CVE-2025-55739 represents a critical authentication bypass flaw within the FreePBX administration interface that operates on top of the Asterisk PBX system. This issue stems from the improper implementation of OAuth token management where identical private keys are distributed across multiple installations through the same RPM or DEB package distribution channels. The flaw affects versions prior to 15.0.13, 16.0.15, and 17.0.3, creating a widespread security risk for organizations utilizing FreePBX as their telephony management platform. The vulnerability specifically impacts systems where the api module has been enabled and configured for remote inbound connections, making it particularly dangerous in environments where external access is permitted.
The technical implementation of this vulnerability resides in the cryptographic key management practices within the FreePBX framework, which aligns with CWE-327 - Use of a Broken or Risky Cryptographic Algorithm and CWE-310 - Cryptographic Issues. When the same OAuth private key is deployed across multiple systems, it fundamentally undermines the security model that relies on unique cryptographic identifiers for authentication token generation. Attackers who obtain access to this shared private key can generate valid JWT tokens that appear authentic to the system's authentication mechanisms. This capability enables them to bypass both REST and GraphQL API authentication layers, potentially allowing full administrative access to the telephony infrastructure. The vulnerability demonstrates poor key distribution practices and violates fundamental security principles of unique identifier generation for cryptographic operations.
The operational impact of this vulnerability extends far beyond simple unauthorized access, as it provides attackers with comprehensive control over telephony systems that may contain sensitive communication data, user credentials, and system configuration information. Systems affected by this vulnerability could be exploited to perform actions such as adding or removing users, modifying dial plans, accessing call records, and potentially redirecting calls to malicious destinations. The remote exploitation capability means that attackers do not require physical access to the systems and can target vulnerable installations over the internet. This vulnerability particularly affects organizations that have configured remote access to their FreePBX systems, as these installations are more likely to be exposed to external threats. The potential for lateral movement within network infrastructures increases when attackers gain access to systems that may be connected to other critical infrastructure components.
Organizations should immediately implement mitigation strategies including upgrading to the patched versions 15.0.13, 16.0.15, and 17.0.3 as specified in the advisory. The upgrade process should include comprehensive testing to ensure that existing configurations remain functional while applying the cryptographic key fixes. Additionally, administrators should review and restrict remote access to FreePBX systems, implementing network segmentation and firewall rules to limit exposure. The vulnerability demonstrates the importance of proper key management practices and highlights the risks associated with distributing identical cryptographic materials across multiple systems. Organizations should also conduct thorough security assessments of their telephony infrastructure to identify any potential exploitation that may have already occurred, as the shared private key could have been compromised through various attack vectors including supply chain attacks or public exposure of the key material.