CVE-2023-25113 is a stack-based buffer overflow vulnerability classified under CWE-121 found in the vtysh_ubus binary of the Milesight UR32L router, specifically version 32.3.0.5. The root cause is the unsafe use of the sprintf function in the set_l2tp function, where the key variable is not properly bounds-checked before being copied into a fixed-size buffer. This allows an attacker with high privileges to craft a malicious HTTP request that overflows the buffer, overwriting adjacent memory on the stack. The overflow can corrupt control flow data, enabling arbitrary code execution with the privileges of the vulnerable process. The vulnerability requires the attacker to have high privileges, such as administrative access to the device’s management interface, but does not require user interaction. The attack vector is network-based via HTTP requests, making remote exploitation feasible if the attacker can reach the management interface. The CVSS v3.1 base score is 7.2, reflecting high impact on confidentiality, integrity, and availability, with low attack complexity and no user interaction required. No public exploits or patches are currently known, but the vulnerability poses a significant risk to the security of affected devices. The vulnerability could be leveraged to take full control of the device, disrupt network operations, or pivot into internal networks.

For European organizations, the impact of CVE-2023-25113 is substantial, especially for those relying on Milesight UR32L routers in critical network infrastructure, such as telecommunications providers, industrial control systems, and enterprise networks. Exploitation could lead to full compromise of the affected device, allowing attackers to intercept, modify, or disrupt network traffic, potentially causing data breaches, service outages, or lateral movement within the network. This could affect confidentiality by exposing sensitive communications, integrity by allowing manipulation of network configurations or data, and availability by causing device crashes or denial of service. Given the network-facing nature of the vulnerability, attackers with administrative access could remotely exploit the flaw to gain persistent control. The lack of patches increases the urgency for organizations to implement compensating controls. The vulnerability also raises concerns for compliance with European data protection regulations, as exploitation could lead to unauthorized data access or service disruptions.

1. Immediately restrict access to the management interface of Milesight UR32L devices to trusted networks and administrators only, using network segmentation and firewall rules. 2. Enforce strong authentication and limit administrative privileges to reduce the risk of high-privilege attackers gaining access. 3. Monitor network traffic for unusual or malformed HTTP requests targeting the vtysh_ubus interface, which could indicate exploitation attempts. 4. Disable or restrict the use of the L2TP configuration interface if not required, reducing the attack surface. 5. Regularly audit device configurations and logs for signs of compromise or anomalous activity. 6. Engage with the vendor for updates and apply security patches as soon as they become available. 7. Consider deploying intrusion detection/prevention systems (IDS/IPS) with signatures for this vulnerability once they are released. 8. Implement network-level protections such as VPNs or IP whitelisting to limit exposure of management interfaces. 9. Educate administrators about the risks of high-privilege access and the importance of secure management practices.