CVE-2025-71025 is a stack 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. A stack overflow occurs when this parameter is manipulated with a crafted request, leading to memory corruption that causes the device to crash or reboot unexpectedly, resulting in a denial of service (DoS). This vulnerability can be triggered remotely by an attacker with network access to the router, without requiring authentication or user interaction. The flaw affects the router's availability by disrupting normal operation and potentially causing network outages. While no public exploits have been reported, the nature of stack overflow vulnerabilities and the lack of authentication requirements make this a credible threat. The Tenda AX-3 is a widely used consumer-grade router, often deployed in home and small office environments, which may lack advanced security controls, increasing exposure risk. The absence of a CVSS score limits precise severity quantification, but the vulnerability's characteristics suggest a significant risk to network availability. No patches or mitigation details have been published yet, emphasizing the need for proactive defensive measures.

For European organizations, especially small businesses and residential users relying on Tenda AX-3 routers, this vulnerability poses a risk of network disruption through denial of service attacks. The loss of router availability can interrupt internet connectivity, affecting business operations, remote work, and access to cloud services. In critical environments, such as healthcare or financial services operating from small offices, such outages could lead to operational delays or data access issues. The vulnerability could be exploited by attackers within the local network or potentially by remote attackers if the router's management interface is exposed to the internet. Given the consumer-grade nature of the device, many affected users may lack the expertise or resources to detect or mitigate the attack promptly. This could lead to prolonged downtime and increased support costs. Additionally, widespread exploitation could contribute to larger-scale network instability in regions with high Tenda router adoption.

1. Immediately restrict access to the router’s management interfaces by disabling remote administration and limiting access to trusted IP addresses. 2. Monitor Tenda’s official channels for firmware updates addressing this vulnerability and apply patches promptly once available. 3. Implement network segmentation to isolate vulnerable routers from critical systems and sensitive data. 4. Employ network intrusion detection systems (NIDS) to monitor for unusual traffic patterns or malformed requests targeting the cloneType2 parameter or related functions. 5. Educate users on the risks of exposing router management interfaces to the internet and encourage secure configuration practices. 6. Consider replacing vulnerable Tenda AX-3 devices with routers from vendors with stronger security track records if timely patching is not feasible. 7. Regularly audit network devices for outdated firmware versions and maintain an inventory to prioritize remediation efforts.