CVE-2022-40107 is a high-severity vulnerability identified in the Tenda i9 router firmware version 1.0.0.8(3828). The vulnerability arises from a buffer overflow condition in the formexeCommand function. Buffer overflow vulnerabilities occur when a program writes more data to a buffer than it can hold, potentially overwriting 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, 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 confidentiality or integrity compromise. The vulnerability is classified under CWE-787 (Out-of-bounds Write), which is a common and dangerous class of memory corruption bugs. No patches or official fixes have been linked or published at the time of this report, and there are no known exploits in the wild. The CVSS v3.1 base score is 7.5, reflecting the high severity due to ease of exploitation and potential to disrupt network availability.

For European organizations, this vulnerability poses a significant risk to network infrastructure relying on Tenda i9 routers, particularly in small to medium-sized enterprises or home office environments where such consumer-grade devices are commonly deployed. A successful exploit could cause network outages by crashing routers, disrupting business operations, communications, and access to critical services. While the vulnerability does not directly expose sensitive data or allow unauthorized control, the resulting denial of service could indirectly impact confidentiality and integrity by forcing fallback to less secure communication channels or delaying security updates. Additionally, critical sectors such as healthcare, finance, and public administration that depend on continuous network availability could face operational disruptions. The lack of authentication requirement and remote exploitability increases the attack surface, making it easier for attackers to target vulnerable devices across the internet or internal networks.

Given the absence of an official patch, European organizations should take immediate steps to mitigate risk. First, identify and inventory all Tenda i9 routers running the affected firmware version 1.0.0.8(3828). Restrict network exposure of these devices by disabling remote management interfaces accessible from the internet and applying strict firewall rules to limit access to trusted IP addresses only. Network segmentation should be enforced to isolate vulnerable devices from critical infrastructure. Monitoring network traffic for unusual patterns targeting router management functions can help detect exploitation attempts. Organizations should also consider replacing or upgrading affected devices to models with updated firmware or from vendors with active security support. If possible, contact Tenda support for any unofficial patches or workarounds. Finally, maintain up-to-date backups and incident response plans to quickly recover from potential DoS incidents.