CVE-2025-52288 is a vulnerability identified in the Access and Mobility Management Function (AMF) component of Open5GS, an open-source implementation of the 5G core network. The flaw arises from an assertion failure within the function ngap_build_downlink_nas_transport located in the source file src/amf/ngap-build.c. This assertion failure can be triggered by an attacker through repeated sequences of User Equipment (UE) connect and disconnect messages. The assertion failure indicates that the software encounters an unexpected state or condition during the processing of these messages, which can cause the AMF component to crash or behave unpredictably. The primary impact of this vulnerability is a denial of service (DoS), where the AMF service becomes unavailable, potentially disrupting 5G network operations. While the description mentions 'other unspecified impacts,' no further technical details or exploit code are currently available, and no known exploits have been observed in the wild. The vulnerability affects Open5GS versions up to 2.7.5, though specific affected versions are not explicitly listed. Since Open5GS is widely used for 5G core network implementations, this vulnerability could impact operators and organizations deploying private or public 5G networks using this software. The lack of a CVSS score and absence of a patch link indicate that remediation guidance may still be pending or under development. Given the nature of the vulnerability, exploitation requires the ability to send crafted UE connect/disconnect message sequences to the AMF, which may require network access or control over UE signaling traffic.

For European organizations, particularly telecom operators and enterprises deploying private 5G networks using Open5GS, this vulnerability poses a significant risk to network availability. The AMF is a critical component responsible for managing UE registration, mobility, and session management. A denial of service in this component can lead to service outages, dropped connections, and degraded user experience for subscribers relying on 5G connectivity. This can affect critical infrastructure sectors such as manufacturing, transportation, healthcare, and public safety that increasingly depend on 5G for low-latency and high-reliability communications. Additionally, disruption of 5G core functions could have cascading effects on other network functions and services integrated with the 5G core. Although no known exploits are currently in the wild, the potential for targeted attacks exists, especially from threat actors aiming to disrupt telecom services or cause operational interruptions. The unspecified 'other impacts' mentioned could imply risks beyond DoS, such as potential information leakage or integrity issues, but these remain unconfirmed. Overall, the vulnerability threatens the confidentiality, integrity, and availability of 5G network services, with availability being the most directly impacted.

To mitigate this vulnerability, European organizations should first monitor Open5GS project communications and security advisories for official patches or updates addressing CVE-2025-52288. Until a patch is available, operators should implement strict network segmentation and access controls to limit exposure of the AMF component to untrusted or external networks, reducing the risk of malicious UE message injection. Deploying anomaly detection systems to monitor unusual UE connect/disconnect message patterns can help identify attempted exploitation attempts early. Network operators should also consider rate limiting or filtering UE signaling messages to prevent repeated rapid connect/disconnect sequences that could trigger the assertion failure. Conducting thorough testing in controlled environments to reproduce the issue and validate mitigations is advisable. Additionally, organizations should review their incident response plans to prepare for potential DoS events affecting 5G core components. Collaboration with vendors and the open-source community to expedite patch development and deployment is critical. Finally, maintaining up-to-date backups and redundancy for core network functions can help ensure service continuity in case of an attack.