CVE-2022-43106 is a critical stack overflow vulnerability identified in the Tenda AC23 router firmware version V16.03.07.45_cn. The flaw exists in the setSchedWifi function, specifically through the schedStartTime parameter. A stack overflow occurs when the input to this parameter exceeds the buffer size allocated on the stack, leading to memory corruption. This vulnerability is classified under CWE-787 (Out-of-bounds Write), which typically allows attackers to overwrite adjacent memory, potentially enabling arbitrary code execution. The CVSS v3.1 base score of 9.8 reflects the severity of this vulnerability, indicating it is remotely exploitable (Attack Vector: Network), requires no privileges (PR:N), no user interaction (UI:N), and impacts confidentiality, integrity, and availability to a high degree (C:H/I:H/A:H). Exploiting this vulnerability could allow an unauthenticated attacker to execute arbitrary code on the affected router, potentially taking full control of the device. This could lead to network compromise, interception or manipulation of traffic, or use of the device as a foothold for further attacks. Although no known exploits are currently reported in the wild, the high severity and ease of exploitation make this a significant threat to users of the affected Tenda AC23 firmware version. The lack of a vendor patch or mitigation guidance in the provided information suggests that affected users remain vulnerable.

For European organizations, this vulnerability poses a substantial risk, especially for those using Tenda AC23 routers in their network infrastructure. Compromise of these routers could lead to unauthorized access to internal networks, interception of sensitive communications, and disruption of network services. Given the critical nature of the flaw, attackers could deploy malware, establish persistent backdoors, or pivot to other internal systems. This is particularly concerning for small and medium enterprises or home office setups that may rely on consumer-grade routers like the Tenda AC23 without robust network segmentation or monitoring. The impact extends beyond confidentiality breaches to potential integrity violations and denial of service, which could disrupt business operations. Additionally, compromised routers could be leveraged in botnets or for launching distributed denial-of-service (DDoS) attacks, affecting broader internet infrastructure within Europe.

Immediate mitigation steps include isolating affected Tenda AC23 devices from critical network segments and the internet where possible. Network administrators should monitor for unusual traffic patterns or signs of compromise originating from these routers. Since no official patch is referenced, users should contact Tenda support to confirm patch availability or firmware updates addressing this vulnerability. If no patch exists, consider replacing affected devices with models from vendors that provide timely security updates. Implement network-level protections such as firewall rules to restrict access to router management interfaces and employ intrusion detection/prevention systems (IDS/IPS) to detect exploitation attempts. Regularly audit router configurations to disable unnecessary services and change default credentials. For organizations, segmenting IoT and consumer-grade devices away from sensitive networks can limit the blast radius of a potential compromise. Finally, maintain up-to-date asset inventories to quickly identify and remediate vulnerable devices.