CVE-2026-2524 identifies a denial of service (DoS) vulnerability in Open5GS version 2.7.6, an open-source 5G core network implementation. The vulnerability resides in the function mme_s11_handle_create_session_response within the Mobility Management Entity (MME) component. This function handles responses related to session creation over the S11 interface, which is critical for managing user sessions in the 5G core network. The flaw allows a remote attacker to send specially crafted messages that manipulate this function, causing the MME process to crash or become unresponsive, resulting in denial of service. The attack vector is network-based (AV:N), requiring no authentication (PR:N) or user interaction (UI:N), making it straightforward to exploit remotely. The vulnerability does not affect confidentiality or integrity but impacts availability by disrupting session management and potentially causing service outages. Although the Open5GS project was notified early, no patch or response has been issued yet, and an exploit has been published publicly, increasing the risk of exploitation. The CVSS 4.0 base score is 6.9, indicating medium severity, reflecting the ease of remote exploitation and the significant impact on service availability but limited scope and no privilege escalation. Open5GS is increasingly adopted by telecom operators and enterprises deploying private 5G networks, making this vulnerability relevant to critical infrastructure.

For European organizations, especially telecom operators and enterprises deploying 5G networks using Open5GS, this vulnerability poses a risk of service disruption. The denial of service in the MME component can interrupt session management, leading to dropped connections, degraded network performance, and potential outages affecting end-users and business-critical applications relying on 5G connectivity. This could impact mobile broadband services, IoT deployments, and enterprise communications. Given the reliance on 5G for digital transformation and critical infrastructure, such disruptions could have cascading effects on economic activities and public services. Additionally, the public availability of exploits increases the risk of opportunistic attacks targeting vulnerable networks. The lack of a patch or official mitigation increases exposure time, necessitating proactive defensive measures. European telecom regulators and operators must consider this vulnerability in their risk assessments and incident response planning to maintain network resilience.

1. Monitor Open5GS project channels closely for official patches or updates addressing CVE-2026-2524 and apply them promptly. 2. In the absence of patches, implement network-level filtering to restrict access to the MME S11 interface, allowing only trusted and authenticated network elements to communicate. 3. Employ anomaly detection and intrusion detection systems to identify unusual traffic patterns targeting the MME component, enabling early detection of exploitation attempts. 4. Consider deploying redundancy and failover mechanisms for the MME to minimize service disruption in case of crashes. 5. Conduct regular security audits and penetration testing focused on 5G core components to identify and remediate similar vulnerabilities proactively. 6. Collaborate with vendors and the open-source community to accelerate patch development and share threat intelligence related to this vulnerability. 7. Educate network operations teams about the vulnerability and signs of exploitation to improve incident response readiness.