CVE-2022-40864 is a critical stack overflow vulnerability identified in Tenda AC15 and AC18 routers running firmware version V15.03.05.19. The vulnerability exists in the function setSmartPowerManagement, which processes requests sent to the /goform/PowerSaveSet endpoint. A stack overflow occurs when the function improperly handles input data, allowing an attacker to overwrite the stack memory. This can lead to arbitrary code execution, denial of service, or complete compromise of the affected device. The vulnerability is remotely exploitable over the network without requiring authentication or user interaction, as indicated by the CVSS vector (AV:N/AC:L/PR:N/UI:N). The severity is rated critical with a CVSS score of 9.8, reflecting high impact on confidentiality, integrity, and availability. The vulnerability is classified under CWE-787 (Out-of-bounds Write), which typically allows attackers to manipulate program execution flow. No patches or fixes are currently linked, and no known exploits have been reported in the wild as of the publication date. However, the ease of exploitation and critical impact make this a significant threat to networks using these router models. Given that routers are often the first line of defense and gateway devices, successful exploitation could allow attackers to intercept, manipulate, or disrupt network traffic, potentially compromising connected devices and sensitive data.

For European organizations, the exploitation of this vulnerability could have severe consequences. Tenda routers are commonly used in small and medium-sized enterprises (SMEs) and residential environments, which may serve as remote offices or home offices for employees. A compromised router could enable attackers to intercept confidential communications, inject malicious payloads, or pivot into internal networks, leading to data breaches, espionage, or ransomware deployment. The critical nature of the vulnerability means that attackers can gain full control over the device without any user interaction or credentials, increasing the risk of widespread compromise. Disruption of network availability could also impact business continuity, especially for organizations relying on stable internet connectivity for operations. Additionally, the lack of available patches increases the window of exposure, making timely mitigation essential. European organizations with remote or distributed workforces using these router models are particularly at risk, as attackers could exploit the vulnerability to bypass perimeter defenses and access sensitive corporate resources.

Given the absence of official patches, European organizations should implement immediate compensating controls. First, identify and inventory all Tenda AC15 and AC18 routers running the vulnerable firmware version. Restrict access to the router management interface by limiting it to trusted IP addresses and disabling remote management if not required. Employ network segmentation to isolate vulnerable routers from critical internal systems and sensitive data. Use firewall rules to block incoming traffic targeting the /goform/PowerSaveSet endpoint or suspicious HTTP requests. Monitor network traffic for unusual activity indicative of exploitation attempts. Where possible, replace vulnerable routers with models from vendors providing timely security updates. If replacement is not feasible, consider deploying network intrusion detection/prevention systems (IDS/IPS) with signatures targeting this vulnerability. Educate IT staff and users about the risks and signs of compromise. Finally, maintain regular backups of router configurations and critical data to enable rapid recovery in case of an incident.