CVE-2022-40105 is a high-severity vulnerability identified in the Tenda i9 router firmware version 1.0.0.8(3828). The flaw is a buffer overflow occurring in the formWifiMacFilterGet function. Buffer overflow vulnerabilities arise when a program writes more data to a buffer than it can hold, potentially overwriting adjacent memory. In this case, the vulnerability allows an attacker to send a specially crafted string to the affected function, which leads to memory corruption. The primary impact of this vulnerability is a Denial of Service (DoS), where the router may crash or become unresponsive, disrupting network connectivity. The CVSS 3.1 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), and no user interaction needed (UI:N). The scope is unchanged (S:U), and the impact affects only availability (A:H) without compromising confidentiality or integrity. No known exploits are reported in the wild, and no patches are currently linked, indicating that mitigation may rely on vendor updates or network-level controls. The vulnerability is categorized under CWE-787, which corresponds to out-of-bounds write errors, a common cause of buffer overflows. Since the affected product is a consumer-grade router, exploitation could be attempted remotely by attackers scanning for vulnerable devices exposed on the internet or within local networks. The lack of authentication requirements and user interaction makes this vulnerability easier to exploit for causing service disruption.

For European organizations, the impact of CVE-2022-40105 can be significant depending on the deployment of Tenda i9 routers within their network infrastructure. A successful exploitation results in a Denial of Service, potentially causing network outages or degraded performance. This can disrupt business operations, especially for small and medium enterprises relying on these routers for internet connectivity or internal segmentation. The DoS could also be leveraged as part of a broader attack campaign to distract or disable network defenses. Although the vulnerability does not allow data theft or code execution, the loss of availability can impact critical services, remote work capabilities, and communication channels. In sectors such as healthcare, finance, or public administration, even temporary network downtime can have regulatory and operational consequences. Additionally, if exploited within home or branch office environments, it could affect employees working remotely, indirectly impacting organizational productivity. The absence of known exploits reduces immediate risk but does not eliminate the threat, especially as attackers often develop exploits for high-severity vulnerabilities over time.

To mitigate CVE-2022-40105, European organizations should first identify any deployment of Tenda i9 routers, specifically version 1.0.0.8(3828). Since no official patches are currently linked, organizations should monitor Tenda's official channels for firmware updates addressing this vulnerability. In the interim, network administrators should implement network segmentation to isolate vulnerable devices from critical infrastructure and restrict access to router management interfaces. Employing firewall rules to block unsolicited inbound traffic to the router's management ports can reduce exposure. Intrusion detection systems (IDS) or intrusion prevention systems (IPS) should be configured to detect anomalous traffic patterns or malformed packets targeting the formWifiMacFilterGet function. Additionally, organizations should consider replacing vulnerable routers with models from vendors that provide timely security updates. Regular network scanning and vulnerability assessments can help detect the presence of vulnerable devices. Finally, educating IT staff about this vulnerability and encouraging vigilance against unusual network behavior can aid in early detection and response.