CVE-2023-25116 is a stack-based buffer overflow vulnerability identified in the Milesight UR32L device firmware version v32.3.0.5. The vulnerability exists in the vtysh_ubus binary, specifically within the set_openvpn_client function, which processes local_virtual_ip and remote_virtual_ip parameters. The root cause is the unsafe use of the sprintf function, which does not perform bounds checking, allowing an attacker to overflow the stack buffer by sending specially crafted HTTP requests. Exploitation requires the attacker to have high privileges on the device, as they must send HTTP requests to the vulnerable service. Successful exploitation can lead to arbitrary code execution, compromising the device’s confidentiality, integrity, and availability. This could allow attackers to execute malicious code remotely, potentially gaining control over the device or disrupting network operations. The vulnerability is classified under CWE-121 (stack-based buffer overflow) and has a CVSS v3.1 base score of 7.2, indicating high severity. Although no public exploits are currently reported, the nature of the vulnerability and its impact make it a significant risk. The affected product, Milesight UR32L, is a network edge device often used in industrial and enterprise environments, making the vulnerability relevant for organizations relying on these devices for secure VPN connectivity and network management.

For European organizations, the impact of CVE-2023-25116 can be substantial. Compromise of Milesight UR32L devices could lead to unauthorized access to internal networks, interception or manipulation of sensitive data, and disruption of critical network services. Given that these devices often serve as VPN gateways or network edge routers, exploitation could provide attackers with a foothold to pivot into deeper network segments. This is particularly concerning for sectors such as energy, manufacturing, transportation, and government agencies that rely on secure and reliable network infrastructure. The potential for arbitrary code execution means attackers could deploy persistent malware, disrupt operations, or exfiltrate confidential information. The requirement for high privileges to exploit somewhat limits the attack surface but does not eliminate risk, especially if internal threat actors or compromised credentials are involved. The absence of known exploits in the wild currently reduces immediate risk but does not preclude future exploitation attempts.

1. Immediate mitigation should focus on upgrading the Milesight UR32L firmware to a version where this vulnerability is patched; if no patch is available, contact the vendor for guidance or workarounds. 2. Restrict access to the device’s HTTP management interface to trusted networks and users only, employing network segmentation and firewall rules to limit exposure. 3. Implement strict access controls and monitor for unusual HTTP requests targeting the vtysh_ubus service, using intrusion detection/prevention systems with custom signatures if possible. 4. Enforce strong authentication and credential management to reduce the risk of privilege escalation that would enable exploitation. 5. Regularly audit device configurations and logs for signs of exploitation attempts or anomalous activity. 6. Consider deploying network-level protections such as web application firewalls (WAFs) that can detect and block malformed HTTP requests targeting this vulnerability. 7. Establish incident response plans that include this vulnerability to ensure rapid containment and remediation if exploitation is detected.