CVE-2026-30059 in Free5GC
Summary
by MITRE • 08/27/2026
An issue in the NAS decoder component of free5gc v4.0.1 allows attackers to cause a Denial of Service (DoS) via a crafted Registration Request message.
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Analysis
by VulDB Data Team • 08/28/2026
The vulnerability identified within the free5GC project, specifically affecting version 4.0.1, resides in the Network Access Authentication NAS decoder component. This open-source implementation of the 5G core network is widely utilized for testing and development purposes due to its compliance with 3GPP standards. The specific flaw allows an attacker to trigger a Denial of Service condition by transmitting a specially crafted Registration Request message. In the context of 5G networks, the Registration procedure is one of the most fundamental signaling processes, initiated when a User Equipment attempts to attach to the network or update its registration status with the Access and Mobility Management Function. The NAS decoder is responsible for parsing these messages to extract critical parameters required for authentication and mobility management.
The technical root cause of this vulnerability lies in improper input validation within the NAS message decoding logic. When processing incoming Registration Request messages, the software fails to adequately verify the structure or length of specific fields before attempting to process them further. This lack of rigorous boundary checking can lead to memory corruption issues, such as buffer overflows or out-of-bounds reads, depending on how the malformed data is handled by the underlying C or Go runtime environment. Consequently, this improper handling causes the NAS decoder to enter an unstable state, leading to a crash of the affected network function process. Since free5GC typically runs these functions in containers or as standalone services, a crash results in immediate service unavailability for that specific component until it is restarted by orchestration tools like Kubernetes.
From an operational perspective, this vulnerability poses a significant risk to the availability and integrity of 5G core infrastructure. An attacker with network access to the control plane interface can exploit this flaw to disrupt critical signaling services. By repeatedly sending crafted Registration Request messages, an adversary can cause continuous crashes or resource exhaustion in the AMF or related NAS handling modules. This effectively creates a Denial of Service condition that prevents legitimate users from registering on the network, thereby blocking voice and data services. In a production environment, such instability could lead to cascading failures if other dependent components rely on the consistent availability of the affected service for session management or policy enforcement decisions.
This vulnerability aligns with CWE-20 Improper Input Validation and potentially CWE-400 Uncontrolled Resource Consumption depending on the specific mechanism causing the crash. In terms of offensive security frameworks, this exploit falls under MITRE ATT&CK technique T1498 Network Denial of Service, specifically within the context of signaling layer attacks against telecommunications infrastructure. The attack vector is classified as network-based, requiring proximity to the control plane traffic but not necessarily direct access to host operating system privileges if the service boundary is breached via the protocol stack itself.
Mitigation strategies for this vulnerability primarily involve upgrading free5GC to a patched version where input validation has been strengthened in the NAS decoder module. Administrators should ensure that all components are updated to versions released after the security advisory addressing CVE details related to this issue. Additionally, implementing network-level controls such as rate limiting on registration requests can help mitigate the impact of automated exploitation attempts by detecting and blocking anomalous signaling traffic patterns before they reach vulnerable services. Security teams should also monitor logs for unusual spikes in NAS message processing errors or service restarts, which may indicate active probing or exploitation attempts against this weakness.