CVE-2026-2522 identifies a memory corruption vulnerability in Open5GS, an open-source 5G core network implementation widely used for mobile network infrastructure. The vulnerability resides in an unspecified function within the /src/mme/esm-build.c source file of the Mobility Management Entity (MME) component. The MME is responsible for key control plane functions such as session management and mobility management in 5G networks. The flaw allows remote attackers to cause memory corruption without requiring authentication or user interaction, implying that exploitation can be initiated over the network by sending crafted messages to the vulnerable MME. Memory corruption can lead to crashes, denial of service, or potentially arbitrary code execution depending on the exploitation complexity and environment. The vulnerability affects all Open5GS versions from 2.7.0 through 2.7.6. Although the exploit details have been publicly disclosed, no confirmed active exploitation has been reported. The CVSS 4.0 vector indicates network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), and low impact on availability (VA:L), with no impact on confidentiality or integrity. The project maintainers have yet to respond or release a patch, increasing the urgency for users to implement interim mitigations. This vulnerability is significant because Open5GS is increasingly adopted by telecom operators and private 5G deployments, and the MME is a critical component whose compromise can disrupt network availability and service continuity.

For European organizations, particularly telecom operators and private 5G network providers using Open5GS, this vulnerability poses a risk of service disruption through denial of service attacks or potentially more severe exploitation if memory corruption is leveraged for code execution. Disruption of the MME component can affect subscriber mobility management and session handling, leading to degraded network performance or outages impacting end users and enterprise customers. Given the remote and unauthenticated nature of the vulnerability, attackers can exploit it without insider access, increasing the threat surface. This could impact critical infrastructure sectors relying on 5G connectivity, including manufacturing, transportation, and emergency services. The lack of a patch and public exploit disclosure heightens the risk of opportunistic attacks. Additionally, reputational damage and regulatory scrutiny may arise if service disruptions occur, especially under stringent European data protection and telecom regulations. Organizations with exposed or poorly segmented 5G core networks are at higher risk.

1. Monitor Open5GS project channels closely for official patches addressing CVE-2026-2522 and apply updates immediately upon release. 2. Implement strict network segmentation and firewall rules to restrict access to the MME component, allowing only trusted management and signaling sources. 3. Deploy intrusion detection/prevention systems (IDS/IPS) with signatures or anomaly detection tuned for unusual MME traffic patterns to detect exploitation attempts. 4. Conduct regular security audits and fuzz testing on Open5GS deployments to identify and remediate memory corruption or other vulnerabilities proactively. 5. Consider deploying Open5GS in containerized or sandboxed environments to limit the impact of potential exploitation. 6. Maintain comprehensive logging and monitoring of MME processes to detect crashes or abnormal behavior indicative of exploitation. 7. Engage with the Open5GS community or commercial support providers for guidance and early access to patches or mitigations. 8. For critical deployments, consider fallback or redundancy mechanisms to maintain service continuity in case of MME failure.