CVE-2025-69208 is an information exposure vulnerability classified under CWE-209, affecting the User Data Repository (UDR) component of free5GC, an open-source 5G core network implementation. Specifically, versions prior to 1.4.1 of free5GC's UDR leak detailed internal parsing errors through the Nnef_PfdManagement service. When malformed input is processed, the NEF component returns error messages containing sensitive details such as invalid characters encountered during JSON parsing (e.g., 'invalid character 'n' after top-level value'). These verbose error messages are sent to remote clients without authentication, enabling attackers to fingerprint the server's software version and internal logic flow. This leakage of internal state information can facilitate reconnaissance activities, potentially aiding in the development of more sophisticated attacks against the 5G core network. The vulnerability has a CVSS 4.0 base score of 2.7, reflecting low severity due to the limited impact and lack of direct exploitation consequences. The issue was addressed in free5GC version 1.4.1 by sanitizing error messages to prevent sensitive information disclosure. No direct application-level workarounds exist, making patching the primary remediation step. The vulnerability does not affect confidentiality, integrity, or availability directly but poses a risk by providing attackers with intelligence about the target system. Given free5GC's role in 5G core networks, this vulnerability is relevant to operators deploying open-source 5G infrastructure components.

The primary impact of CVE-2025-69208 is the exposure of internal error details that can assist attackers in fingerprinting the free5GC UDR component and understanding its internal logic. While this does not directly compromise user data confidentiality, integrity, or system availability, it lowers the barrier for attackers to perform targeted reconnaissance. By gaining insights into parsing logic and software versions, adversaries can tailor subsequent attacks, potentially increasing the risk of exploitation of other vulnerabilities or misconfigurations. For organizations operating 5G core networks with free5GC, this information leakage could facilitate more effective cyberattacks against critical telecommunications infrastructure. Although no known exploits are currently reported, the vulnerability could be leveraged in advanced persistent threat scenarios or by nation-state actors targeting 5G networks. The impact is thus primarily on the security posture and attack surface reduction rather than immediate operational disruption.

The definitive mitigation for CVE-2025-69208 is to upgrade free5GC to version 1.4.1 or later, where the error handling has been corrected to prevent sensitive information leakage. Organizations should implement a patch management process to promptly apply this update in all affected environments. Additionally, network-level controls such as restricting access to the Nnef_PfdManagement service to trusted management networks or VPNs can reduce exposure. Employing Web Application Firewalls (WAFs) or Intrusion Detection/Prevention Systems (IDS/IPS) with rules to detect and block malformed requests that trigger parsing errors may help limit information leakage. Logging and monitoring for unusual error message requests can aid in early detection of reconnaissance attempts. Since no application-level workaround exists, prioritizing patch deployment and minimizing unnecessary exposure of management interfaces are critical. Finally, organizations should conduct security assessments of their 5G core deployments to identify and remediate similar information disclosure issues.