CVE-2025-71025 is a stack-based buffer overflow vulnerability identified in the Tenda AX-3 router firmware version 16.03.12.10_CN. The vulnerability resides in the handling of the cloneType2 parameter within the fromAdvSetMacMtuWan function. When processing this parameter, the function fails to properly validate input size, leading to a stack overflow condition. This flaw can be triggered remotely over the network without requiring any authentication or user interaction, making it accessible to unauthenticated attackers. Exploitation results in a denial of service (DoS) condition by crashing or destabilizing the router, thereby disrupting network availability. The vulnerability is classified under CWE-121 (Stack-based Buffer Overflow). The CVSS v3.1 base score is 7.5, reflecting a high severity due to the network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), and impact limited to availability (A:H) without affecting confidentiality or integrity. No patches or official fixes have been published yet, and no exploits have been observed in the wild. The vulnerability's presence in a widely used consumer and small business router model raises concerns about potential widespread impact if weaponized. The lack of authentication requirements and ease of triggering the overflow make it a critical point of concern for network administrators relying on Tenda AX-3 devices.

For European organizations, exploitation of CVE-2025-71025 could lead to significant network outages due to denial of service on Tenda AX-3 routers. This disruption can affect business continuity, especially for small and medium enterprises or branch offices that depend on these routers for internet connectivity and internal network segmentation. The loss of availability may interrupt critical services, remote work capabilities, and communications. While the vulnerability does not compromise data confidentiality or integrity, the resulting downtime could indirectly impact operational efficiency and customer trust. Additionally, organizations in sectors such as finance, healthcare, and public services that require high network reliability may face compliance and regulatory challenges if service disruptions occur. The absence of known exploits currently provides a window for proactive mitigation, but the ease of exploitation and network exposure necessitate urgent attention to prevent potential attacks targeting European networks.

1. Monitor Tenda's official channels for firmware updates addressing CVE-2025-71025 and apply patches immediately upon release. 2. Implement network-level filtering to block or restrict access to the management interfaces of Tenda AX-3 routers from untrusted networks, especially the WAN side. 3. Employ intrusion detection and prevention systems (IDS/IPS) with signatures or anomaly detection capabilities to identify and block malformed requests targeting the cloneType2 parameter or related functions. 4. Segment networks to isolate critical assets and reduce the attack surface exposed to vulnerable routers. 5. Conduct regular vulnerability assessments and penetration testing focusing on network devices to detect exploitation attempts. 6. Where feasible, consider replacing Tenda AX-3 routers with devices from vendors with a stronger security track record and timely patch management. 7. Educate IT staff on monitoring router logs and unusual network behavior that may indicate exploitation attempts. 8. Restrict remote management access using VPNs or secure channels with strong authentication to prevent unauthorized triggering of the vulnerability.