CVE-2025-10942 is a remote buffer overflow vulnerability found in the H3C Magic B3 product, specifically affecting versions up to 100R002. The vulnerability resides in the AddMacList and EditMacList functions handled by the /goform/aspForm endpoint, where improper handling of the 'param' argument allows an attacker to overflow a buffer. This flaw can be exploited remotely without any authentication or user interaction, making it highly accessible to attackers. The buffer overflow can lead to arbitrary code execution, potentially allowing attackers to fully compromise the device, affecting confidentiality, integrity, and availability. The vulnerability has a CVSS 4.0 base score of 8.7, indicating high severity, with low attack complexity and no privileges required. Although no active exploitation has been reported, a public exploit is available, increasing the risk of imminent attacks. The vendor H3C was contacted but did not respond, and no patches have been released yet, leaving affected devices exposed. The Magic B3 is commonly used in enterprise and service provider networks, making this vulnerability critical for network security. The lack of vendor response and public exploit availability necessitate immediate defensive measures by affected organizations.

For European organizations, exploitation of CVE-2025-10942 could result in full compromise of network devices running H3C Magic B3, leading to unauthorized access, data breaches, network disruption, and potential lateral movement within corporate networks. This could impact critical infrastructure, enterprise communications, and service provider environments. The vulnerability threatens confidentiality by allowing attackers to access sensitive network configurations and data, integrity by enabling malicious modifications, and availability by potentially causing device crashes or denial of service. Given the remote, unauthenticated nature of the exploit, attackers can target exposed devices over the internet or internal networks, increasing the attack surface. The absence of vendor patches and the availability of public exploits heighten the risk of widespread attacks, especially in sectors relying on H3C hardware for network management. Disruption of these devices could affect business continuity and critical services across Europe.

Since no official patches are currently available, European organizations should implement immediate compensating controls. These include isolating H3C Magic B3 devices from untrusted networks and restricting access to management interfaces using network segmentation and firewall rules. Deploy intrusion detection/prevention systems (IDS/IPS) with signatures or heuristics to detect exploit attempts targeting /goform/aspForm endpoints. Implement strict input validation and filtering at network boundaries to block malformed requests attempting buffer overflow exploitation. Monitor network traffic and device logs for unusual activity related to MAC list modifications. Consider temporary disabling or restricting the vulnerable AddMacList/EditMacList functionality if feasible. Engage with H3C or authorized vendors for updates and patches, and plan for rapid deployment once available. Conduct thorough asset inventories to identify all affected devices and prioritize remediation efforts accordingly. Additionally, maintain up-to-date backups and incident response plans to mitigate potential compromise consequences.