CVE-2025-69250 affects the Unified Data Management (UDM) component of free5gc, an open-source 5G core network implementation. Specifically, versions up to and including 1.4.1 of free5gc UDM improperly handle exceptional conditions when processing invalid pduSessionId inputs in the Nudm_UECM DELETE service. Instead of gracefully handling errors, the service leaks detailed internal error messages such as strconv.ParseInt parsing errors back to remote clients. This behavior reveals sensitive implementation details that can be leveraged for service fingerprinting and reconnaissance by attackers. The root cause is an improper check for unusual or exceptional conditions (CWE-754) combined with insufficient input validation (CWE-20). The vulnerability can be exploited remotely without authentication or user interaction, increasing its accessibility to attackers. Although the vulnerability does not directly allow unauthorized data access or service disruption, the information disclosure can aid attackers in crafting targeted attacks against the 5G core network infrastructure. The issue has been addressed in free5gc/udm pull request 76, which corrects error handling to prevent leakage of internal messages. No direct application-level workarounds exist, so applying the official patch is the recommended mitigation. This vulnerability highlights the importance of robust error handling and input validation in critical telecom infrastructure components.

The primary impact of CVE-2025-69250 is information disclosure through detailed error message leakage. This exposure can facilitate service fingerprinting, allowing attackers to identify the presence and version of free5gc UDM components in 5G core networks. While it does not directly compromise confidentiality, integrity, or availability, the reconnaissance advantage gained can enable more precise and effective follow-on attacks, such as targeted exploitation of other vulnerabilities or network mapping. For organizations operating 5G core networks using free5gc, this vulnerability increases the attack surface and reduces operational security. Given the critical role of UDM in subscriber data management and authentication workflows, any compromise or targeted attack enabled by reconnaissance could have severe downstream effects. The vulnerability's ease of exploitation without authentication or user interaction further elevates its risk profile. However, the lack of known exploits in the wild currently limits immediate threat. Organizations should treat this vulnerability seriously to maintain the security posture of their 5G infrastructure.

1. Apply the official patch from free5gc/udm pull request 76 promptly to eliminate detailed error message leakage. 2. Implement network-level filtering and access controls to restrict exposure of the UDM Nudm_UECM DELETE service to trusted management networks only. 3. Employ Web Application Firewalls (WAFs) or API gateways capable of sanitizing error responses and blocking malformed pduSessionId inputs. 4. Conduct thorough input validation and error handling reviews across all 5G core network components to prevent similar information disclosure issues. 5. Monitor network traffic for abnormal requests targeting the Nudm_UECM DELETE endpoint to detect potential reconnaissance attempts. 6. Maintain up-to-date vulnerability management processes to quickly identify and remediate emerging issues in open-source telecom software. 7. Engage in regular security testing, including fuzzing and penetration testing, focused on input validation and error handling in critical telecom services. 8. Collaborate with the free5gc community to stay informed about security updates and best practices.