CVE-2026-30068 in Free5GC
Summary
by MITRE • 08/27/2026
Improper input validation in the HandleUpdate function (/sbi/parameter_provision.go) of free5gc v4.0.1 allows attackers to cause a Denial of Service (DoS) via a crafted input.
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Analysis
by VulDB Data Team • 08/27/2026
The vulnerability identified within the free5GC open-source 5G core network implementation represents a critical failure in application-level security controls, specifically targeting the HandleUpdate function located in the parameter_provision.go module. As an open-source project designed to facilitate rapid deployment and testing of fifth-generation mobile networks, free5GC serves as a foundational component for many academic research projects, private LTE/5G deployments, and network simulation environments. The specific flaw resides in how this particular handler processes incoming data structures intended for parameter provisioning. In secure software architecture, any function responsible for ingesting external or semi-trusted input must rigorously validate that the received data conforms to expected formats, types, lengths, and logical constraints before processing it further into system memory or configuration states. The absence of such validation mechanisms in this specific code path creates a direct attack vector for malicious actors who can interact with the 5G core network interfaces.
From a technical perspective, the root cause is classified as Improper Input Validation, which aligns directly with CWE-20: Improper Input Validation within the Common Weakness Enumeration taxonomy. This weakness occurs when software receives input data but fails to verify that it meets defined requirements before processing. In the context of free5GC v4.0.1, the HandleUpdate function likely accepts parameters related to network configuration or subscriber management without sufficiently checking for boundary conditions, type mismatches, or malformed structures. When an attacker submits a crafted payload containing unexpected data types, excessively long strings, null bytes in inappropriate contexts, or logically inconsistent parameter sets, the application may fail to handle these anomalies gracefully. Instead of returning a standardized error code and rejecting the request, the unvalidated input propagates through the system logic, potentially triggering runtime errors, memory corruption issues such as buffer overflows, or infinite loops depending on how the underlying Go runtime handles the malformed data structures during deserialization or processing.
The operational impact of this vulnerability is primarily centered around Denial of Service (DoS), corresponding to CWE-400: Uncontrolled Resource Consumption. By exploiting this input validation flaw, an attacker can cause the free5GC instance to crash, hang, or consume excessive CPU and memory resources until it becomes unresponsive. In a production 5G core environment, such instability is catastrophic as it disrupts essential network functions including authentication, mobility management, session establishment, and policy control. Even in testbed environments where free5GC is commonly deployed for research purposes, this vulnerability undermines the reliability of experiments and simulations that depend on continuous availability of the core network components. The ability to trigger a DoS condition remotely or locally via crafted inputs means that any entity with access to the affected API endpoints can effectively take down the entire 5G infrastructure managed by that instance, leading to significant service disruption and potential data loss if stateful connections are abruptly terminated without proper cleanup procedures.
This vulnerability maps closely to MITRE ATT&CK technique T1498: Network Denial of Service, which describes actions taken to disrupt or deny services to legitimate users. While the primary intent here is resource exhaustion leading to service unavailability rather than complex exploitation for data theft, the mechanism remains a potent tool in an attacker's arsenal against network infrastructure. The lack of robust input sanitization means that even low-privilege attackers who can send HTTP requests to the affected endpoint can achieve high-impact results by simply sending malformed packets repeatedly or once with specific triggering conditions. This highlights a broader trend in open-source telecommunications software where rapid development cycles sometimes outpace rigorous security auditing, leaving critical pathways exposed to basic but effective exploitation techniques.
To mitigate this vulnerability and prevent similar issues in future versions of free5GC, developers must implement strict input validation routines within the HandleUpdate function. This involves defining clear schemas for all expected parameters using libraries such as Go's validator package or custom struct tags that enforce type checking, length limits, and format constraints before any business logic is executed. Additionally, implementing panic recovery mechanisms can help contain crashes caused by unexpected inputs, allowing the service to recover gracefully rather than terminating entirely. From a defensive posture perspective, organizations deploying free5GC should ensure they are running patched versions of the software where this validation has been corrected. Furthermore, network segmentation and firewall rules restricting access to internal 5G core APIs from untrusted networks provide an additional layer of defense-in-depth, ensuring that even if input validation fails, external attackers cannot easily reach the vulnerable endpoints. Regular security code reviews focusing on data handling paths in critical infrastructure components are essential to maintaining the integrity and availability of next-generation mobile network deployments.