The vulnerability identified as CVE-2025-71019 affects the Tenda AX-1806 router firmware version 1.0.0.1. It is a stack overflow flaw located in the processing of the wanSpeed parameter within the sub_65B5C function. Stack overflow vulnerabilities occur when a program writes more data to a buffer located on the stack than it can hold, potentially overwriting adjacent memory and causing unpredictable behavior. In this case, the crafted request targeting the wanSpeed parameter can overflow the stack, leading to a Denial of Service (DoS) by crashing the router or causing it to become unresponsive. The vulnerability does not require authentication or user interaction, making it easier for remote attackers to exploit if they can reach the device's WAN interface. No CVSS score has been assigned yet, and no patches or known exploits are currently available. The lack of authentication and the direct impact on device availability make this a significant risk, especially for networks relying on these routers for internet connectivity. The vulnerability's exploitation could disrupt business operations by interrupting internet access or internal network routing. Since the Tenda AX-1806 is a consumer-grade router, it may also be present in small to medium enterprise environments, increasing the potential attack surface. The absence of patches necessitates proactive mitigation until vendor updates are released.

For European organizations, exploitation of this vulnerability could lead to network outages or degraded internet connectivity due to router crashes. This can affect business continuity, especially for organizations relying on stable WAN connections for cloud services, remote work, or critical communications. The DoS condition could also be leveraged as part of a larger attack campaign to disrupt services or as a diversion for other malicious activities. Small and medium enterprises using Tenda AX-1806 routers are particularly vulnerable, as these devices may lack advanced security controls or monitoring. Critical infrastructure sectors such as telecommunications, finance, and healthcare could face operational risks if these routers are deployed in their network perimeters. Additionally, the ease of exploitation without authentication increases the likelihood of opportunistic attacks from external threat actors. The absence of known exploits in the wild currently limits immediate risk, but the vulnerability's public disclosure may prompt attackers to develop exploits. Overall, the impact is primarily on availability, with potential cascading effects on organizational operations and service delivery.

1. Immediately restrict WAN-side access to the router's management interfaces to trusted IP addresses or disable remote management if not required. 2. Monitor network traffic for unusual or malformed requests targeting the wanSpeed parameter or other router management endpoints. 3. Segment networks to isolate critical systems from devices running vulnerable firmware to contain potential disruptions. 4. Maintain an inventory of Tenda AX-1806 devices within the organization and prioritize their monitoring and protection. 5. Engage with Tenda support channels to obtain information on forthcoming patches or firmware updates addressing this vulnerability. 6. Implement network-level protections such as intrusion detection/prevention systems (IDS/IPS) configured to detect anomalous WAN traffic patterns. 7. Prepare incident response plans to quickly isolate or reboot affected devices to restore service in case of exploitation. 8. Educate IT staff about this vulnerability and encourage vigilance for related security advisories. 9. Consider deploying alternative or updated networking equipment if patching is delayed or unavailable. 10. Regularly back up router configurations to enable rapid recovery after remediation.