CVE-2022-40102 is a high-severity vulnerability identified in the firmware version 1.0.0.8(3828) of the Tenda i9 router. The vulnerability arises from a buffer overflow condition in the formwrlSSIDset function. Buffer overflow vulnerabilities occur when a program writes more data to a buffer than it can hold, which can corrupt adjacent memory. In this case, an attacker can exploit this flaw by sending a specially crafted string to the vulnerable function, causing the device to crash or reboot unexpectedly, resulting in a Denial of Service (DoS) condition. The vulnerability does not require any authentication or user interaction, and it can be exploited remotely over the network (AV:N), with low attack complexity (AC:L). The impact is limited to availability (A:H), with no direct impact on confidentiality or integrity. No known exploits are currently reported in the wild, and no official patches or vendor advisories have been published yet. The vulnerability is classified under CWE-787 (Out-of-bounds Write), which is a common and critical class of memory corruption bugs. Given the nature of the device—a consumer or small office router—successful exploitation could disrupt network connectivity for affected users, potentially impacting business operations or home internet access.

For European organizations, the impact of this vulnerability primarily concerns network availability. Tenda routers, including the i9 model, are used in various markets including Europe, often in small and medium-sized enterprises (SMEs) and residential environments. A successful DoS attack could interrupt internet access or internal network connectivity, leading to operational downtime, loss of productivity, and potential disruption of critical services reliant on continuous network availability. While the vulnerability does not allow data theft or device takeover, the loss of network service can indirectly affect business continuity and incident response capabilities. Additionally, if attackers use this vulnerability as part of a larger multi-vector attack, it could serve as a stepping stone to further compromise. The lack of authentication and user interaction requirements makes it easier for attackers to exploit remotely, increasing the risk for organizations with exposed or poorly segmented networks.

Given the absence of an official patch, European organizations should implement the following specific mitigations: 1) Network Segmentation: Isolate Tenda i9 routers from critical network segments to limit the impact of a DoS attack. 2) Access Control: Restrict remote management access to the router by disabling WAN-side administration and limiting management interfaces to trusted IP addresses or VPN connections. 3) Traffic Filtering: Deploy network intrusion prevention systems (IPS) or firewall rules to detect and block malformed packets targeting the formwrlSSIDset function or suspicious traffic patterns indicative of exploitation attempts. 4) Monitoring and Logging: Enable detailed logging on network devices and monitor for unusual router reboots or service interruptions that may indicate exploitation attempts. 5) Vendor Engagement: Engage with Tenda support channels to request firmware updates or official patches and subscribe to security advisories for timely updates. 6) Device Replacement: For high-risk environments, consider replacing vulnerable Tenda i9 routers with devices from vendors with stronger security track records and active patch management. 7) Incident Response Preparedness: Develop and test response plans for network outages caused by DoS attacks to minimize downtime and impact.