CVE-2022-40104 is a high-severity buffer overflow vulnerability identified in the Tenda i9 router firmware version 1.0.0.8(3828). The vulnerability arises from improper handling of input in the formwrlSSIDget function, which processes SSID-related data. An attacker can exploit this flaw by sending a specially crafted string to the vulnerable function, causing a buffer overflow condition. This overflow can lead to a Denial of Service (DoS) state, where the device becomes unresponsive or crashes, disrupting network connectivity. 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 reported. No known exploits are currently in the wild, and no patches have been published by the vendor at the time of this report. The vulnerability is classified under CWE-787 (Out-of-bounds Write), indicating that the buffer overflow occurs due to writing data outside the allocated memory bounds, which can destabilize the device's operation.

For European organizations, the exploitation of CVE-2022-40104 could result in network outages or degraded performance due to router crashes or reboots. Since Tenda routers are often used in small to medium-sized enterprises and home office environments, a successful attack could disrupt business operations, remote work capabilities, and internet access. Although the vulnerability does not directly compromise data confidentiality or integrity, the loss of availability can have cascading effects, such as interruption of critical communications, delays in business processes, and potential loss of productivity. Additionally, if attackers combine this DoS vulnerability with other attack vectors, it could facilitate further exploitation or lateral movement within a network. The lack of authentication requirement and remote exploitability increases the risk, especially in environments where these routers are exposed to untrusted networks or the internet without adequate perimeter defenses.

Given the absence of an official patch, European organizations should implement specific mitigations to reduce exposure. First, isolate Tenda i9 routers from direct internet access by placing them behind firewalls or VPNs, restricting access to trusted IP ranges only. Disable any unnecessary remote management interfaces and services to minimize attack surface. Network segmentation should be employed to separate critical systems from the router's management network. Monitoring network traffic for unusual patterns targeting the router's SSID management functions can provide early detection of exploitation attempts. Organizations should also consider replacing vulnerable Tenda i9 devices with models from vendors that provide timely security updates and have a strong security track record. Finally, maintain up-to-date inventories of network devices to ensure rapid identification and response to vulnerabilities like CVE-2022-40104.