CVE-2025-70656 is a stack-based buffer overflow vulnerability identified in the Tenda AX-1806 router firmware version 1.0.0.1. The vulnerability resides in the function sub_65B5C, specifically in the processing of the 'mac' parameter. An attacker can craft a specially formed request that overflows the stack buffer, leading to a denial of service (DoS) by crashing or causing the router to become unresponsive. The vulnerability is remotely exploitable without any authentication or user interaction, making it accessible to any attacker with network access to the device. The CVSS v3.1 score of 7.5 reflects the high impact on availability (A:H) while confidentiality and integrity remain unaffected (C:N/I:N). The attack vector is network-based (AV:N), with low attack complexity (AC:L), and no privileges required (PR:N). This vulnerability is categorized under CWE-121 (Stack-based Buffer Overflow), a common and well-understood class of memory corruption bugs. Although no public exploits or patches are currently available, the vulnerability poses a significant risk to network stability, especially in environments where these routers are deployed as critical network infrastructure. The lack of authentication requirements and ease of exploitation increase the threat level, as attackers can remotely disrupt network connectivity or services dependent on the router. The absence of patch links indicates that vendors have not yet released fixes, underscoring the need for proactive mitigation measures.

For European organizations, exploitation of CVE-2025-70656 could result in denial of service conditions affecting network availability. This may disrupt business operations, especially for enterprises and service providers relying on Tenda AX-1806 routers for internet connectivity or internal network routing. Critical infrastructure sectors such as telecommunications, finance, healthcare, and government services could experience outages or degraded service quality. The impact is primarily on availability, with no direct compromise of data confidentiality or integrity. However, prolonged or repeated DoS attacks could indirectly affect operational continuity and incident response capabilities. The vulnerability's remote and unauthenticated nature increases the risk of widespread exploitation, particularly if attackers scan for vulnerable devices exposed to the internet or accessible within corporate networks. European organizations with limited network segmentation or exposed management interfaces are especially vulnerable. Additionally, the lack of available patches means that affected entities must rely on compensating controls until vendor updates are released.

1. Immediately restrict access to the Tenda AX-1806 router management interfaces by implementing network segmentation and firewall rules that limit access to trusted IP addresses only. 2. Disable remote management features if not required, or restrict them to secure VPN connections to prevent unauthorized external access. 3. Monitor network traffic for unusual or malformed requests targeting the 'mac' parameter or other router management endpoints, using intrusion detection/prevention systems (IDS/IPS). 4. Maintain an inventory of all Tenda AX-1806 devices within the organization to identify and prioritize vulnerable units. 5. Engage with the vendor for updates on patches or firmware upgrades addressing this vulnerability and plan timely deployment once available. 6. Consider temporary replacement or isolation of vulnerable devices in critical network segments until patches are applied. 7. Educate network administrators about the vulnerability and recommended operational security practices to reduce exposure. 8. Implement network-level rate limiting or anomaly detection to mitigate potential DoS attempts exploiting this vulnerability.