CVE-2022-43105 is a critical stack overflow vulnerability identified in the Tenda AC23 router firmware version V16.03.07.45_cn. The vulnerability arises from improper handling of the 'shareSpeed' parameter within the 'fromSetWifiGusetBasic' function. Specifically, the function fails to properly validate or sanitize the input length or content of the 'shareSpeed' parameter, leading to a stack-based buffer overflow (CWE-787). This type of vulnerability allows an attacker to overwrite parts of the stack memory, potentially enabling arbitrary code execution, denial of service, or system compromise. The CVSS v3.1 base score of 9.8 reflects the critical nature of this flaw, with an attack vector that is network-based (AV:N), requiring no privileges (PR:N) and no user interaction (UI:N). The impact includes complete confidentiality, integrity, and availability loss (C:H/I:H/A:H). Although no known exploits are currently reported in the wild, the severity and ease of exploitation make this a significant threat. The vulnerability affects the Tenda AC23 router, a consumer-grade wireless access point device, commonly used in home and small office environments. The lack of a patch link suggests that a fix may not yet be publicly available or widely distributed, increasing the urgency for mitigation and monitoring.

For European organizations, especially small and medium enterprises (SMEs) and home office users relying on Tenda AC23 routers, this vulnerability poses a substantial risk. Exploitation could lead to unauthorized network access, interception or manipulation of sensitive data, disruption of internet connectivity, and potential pivoting into internal networks. Given the router's role as a network gateway, compromise could undermine the security of connected devices, including corporate endpoints, IoT devices, and telework infrastructure. This is particularly concerning in sectors with strict data protection requirements such as finance, healthcare, and critical infrastructure. The vulnerability's network-exploitable nature means attackers can target devices remotely without authentication, increasing the attack surface. Additionally, the absence of known exploits does not preclude future weaponization, and the critical CVSS score indicates a high likelihood of exploitation attempts once exploit code becomes available.

European organizations and users should immediately assess their network environments for the presence of Tenda AC23 routers running the vulnerable firmware version. Practical mitigation steps include: 1) Isolate affected devices from critical network segments to limit potential lateral movement. 2) Disable remote management interfaces or restrict access to trusted IP addresses to reduce exposure. 3) Monitor network traffic for unusual activity indicative of exploitation attempts, such as malformed packets targeting the 'shareSpeed' parameter or unexpected router behavior. 4) Regularly check for firmware updates from Tenda and apply patches promptly once available. 5) If patching is not immediately possible, consider replacing vulnerable devices with alternative routers from vendors with active security support. 6) Implement network segmentation and robust firewall rules to contain potential breaches. 7) Educate users about the risks of using outdated router firmware and encourage routine device maintenance. These targeted actions go beyond generic advice by focusing on device-specific controls and proactive monitoring tailored to this vulnerability.