CVE-2026-30069 in Free5GC
Summary
by MITRE • 08/27/2026
A NULL pointer dereference in the UDMC registration handler component of free5gc v4.0.1 allows attackers to cause a Denial of Service (DoS) via supplying crafted payload.
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Analysis
by VulDB Data Team • 08/27/2026
The vulnerability identified within the free5GC implementation, specifically affecting version 4.0.1, resides in the User Data Management Component registration handler. This component is critical for managing subscriber data and handling authentication procedures during network access requests. The core technical flaw is a NULL pointer dereference that occurs when the system processes specific input parameters associated with user equipment registration. In standard software engineering practices, functions interacting with external inputs or complex object structures must validate pointers before attempting to access memory addresses they reference. However, in this instance, the handler fails to adequately verify whether certain data structures are properly initialized or populated before proceeding with subsequent operations that rely on these references.
When an attacker supplies a crafted payload designed to trigger this specific code path without providing the expected valid object references, the application attempts to dereference a NULL pointer. In most operating systems and runtime environments, accessing memory at address zero is prohibited for security reasons. Consequently, this illegal access triggers a segmentation fault or similar critical exception within the process space of the free5GC service. Because network-facing services typically run as long-lived processes handling multiple concurrent connections, such an abrupt termination results in immediate unavailability of that specific service instance. This constitutes a classic Denial of Service condition where availability is compromised without requiring any form of authentication or privilege escalation from the attacker.
From a threat modeling perspective, this vulnerability aligns with CWE-476, which defines NULL Pointer Dereference as a design error where software fails to check for null pointers before using them. The operational impact extends beyond simple service interruption; in a 5G core network environment, stability is paramount. A crash in the User Data Management component can disrupt authentication flows and subscriber data retrieval, potentially affecting other dependent services that rely on consistent availability of user context information. Attackers can exploit this by sending malformed registration requests repeatedly or strategically to ensure sustained disruption of service for legitimate users attempting to connect to the 5G network.
Mitigation strategies should focus primarily on patching the underlying source code to enforce strict input validation and pointer safety checks within the UDMC registration handler. Developers must implement defensive programming techniques that verify all pointers are non-null before dereferencing them, particularly when handling data derived from external network messages. Additionally, deploying runtime protection mechanisms such as Address Sanitizers during testing phases can help identify these issues earlier in the development lifecycle. For immediate operational resilience, implementing rate limiting on registration requests and configuring automatic service restarts with health checks can mitigate the impact of successful exploitation attempts until a permanent code fix is deployed. This issue highlights the importance of rigorous static analysis and fuzzing techniques when developing critical infrastructure components for next-generation mobile networks.