CVE-2023-25120 is a stack-based buffer overflow vulnerability identified in the Milesight UR32L device firmware version v32.3.0.5. The flaw exists in the vtysh_ubus binary, specifically within the set_dmvpn function that processes the cisco_secret variable. The root cause is the unsafe use of the sprintf function, which does not properly limit the size of data copied into a buffer, allowing an attacker to overflow the stack. This overflow can be triggered by sending a specially crafted HTTP request to the device. The vulnerability requires the attacker to have high privileges on the device, indicating that initial authentication or elevated access is necessary. Exploitation can lead to arbitrary code execution, enabling the attacker to execute malicious payloads, potentially taking full control of the device. The CVSS v3.1 base score is 7.2, reflecting high severity with network attack vector, low attack complexity, required privileges, no user interaction, and high impact on confidentiality, integrity, and availability. No patches or public exploits are currently reported, but the risk remains significant due to the critical nature of the device in network infrastructure. The vulnerability is classified under CWE-121 (stack-based buffer overflow), a common and dangerous software weakness that can lead to severe security breaches if exploited.

For European organizations, the impact of this vulnerability can be substantial, especially for those relying on Milesight UR32L devices for critical network routing and VPN connectivity. Successful exploitation could allow attackers to execute arbitrary code, potentially leading to full device compromise. This could result in unauthorized access to internal networks, interception or manipulation of sensitive data, disruption of network services, and lateral movement within the network. The confidentiality, integrity, and availability of organizational data and services could be severely affected. Given the device’s role in network infrastructure, exploitation could also impact business continuity and operational stability. Sectors such as telecommunications, critical infrastructure, government, and enterprises with distributed networks are particularly at risk. The requirement for high privileges limits the attack surface but does not eliminate risk, as insider threats or compromised credentials could facilitate exploitation. The absence of known public exploits currently reduces immediate risk but does not preclude future attacks.

European organizations should take immediate steps to mitigate this vulnerability. First, verify if Milesight UR32L devices running firmware v32.3.0.5 are deployed within the network. If so, restrict administrative access to these devices using network segmentation and strong access controls to limit exposure to only trusted personnel and systems. Implement strict authentication mechanisms and monitor for unusual access patterns or HTTP requests targeting the vtysh_ubus service. Since no official patch is currently available, consider contacting the vendor for updates or workarounds. Disable or restrict the affected set_dmvpn functionality if feasible. Employ network intrusion detection systems (NIDS) with custom signatures to detect anomalous HTTP requests that could exploit this vulnerability. Regularly audit device configurations and logs for signs of exploitation attempts. Additionally, enforce strong credential management policies to prevent privilege escalation. Plan for timely firmware updates once patches are released and test them in controlled environments before deployment. Maintain an incident response plan tailored to network device compromises.