CVE-2022-44366 is a critical buffer overflow vulnerability identified in the Tenda i21 router firmware version V1.0.0.14(4656). The vulnerability exists in the handling of requests to the /goform/setDiagnoseInfo endpoint. A buffer overflow occurs when the application writes more data to a buffer than it can hold, potentially overwriting adjacent memory. This can lead to arbitrary code execution, denial of service, or system compromise. 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 impact on confidentiality, integrity, and availability is high, as successful exploitation can allow an attacker to execute arbitrary code with system-level privileges, potentially taking full control of the affected device. 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 vendor advisories are currently listed, and no known exploits have been reported in the wild as of the published date. However, the high CVSS score of 9.8 reflects the critical nature of this vulnerability and the ease with which it can be exploited remotely without any authentication barriers. Given that Tenda i21 is a consumer and small office/home office (SOHO) router, exploitation could allow attackers to compromise network traffic, launch further attacks on internal networks, or use the device as a foothold for persistent access or botnet recruitment.

For European organizations, especially small and medium enterprises (SMEs) and home office users relying on Tenda i21 routers, this vulnerability poses a significant risk. Successful exploitation could lead to full compromise of the router, allowing attackers to intercept, modify, or redirect network traffic, undermining confidentiality and integrity of communications. This could facilitate data theft, espionage, or injection of malicious payloads into the network. The availability of the network could also be disrupted by denial-of-service conditions caused by exploitation. Given the router’s role as a gateway device, the impact extends beyond the device itself to all connected systems, potentially enabling lateral movement within corporate or home networks. The lack of authentication requirement and remote exploitability increases the risk of widespread attacks, especially if automated exploit tools emerge. The absence of patches means organizations must rely on mitigations to reduce exposure. The impact is particularly critical for organizations handling sensitive data or critical infrastructure, where network compromise could have cascading effects on operational continuity and data protection compliance.

1. Network Segmentation: Isolate Tenda i21 routers from critical network segments to limit potential lateral movement if compromised. 2. Access Control: Restrict remote management access to the router by disabling WAN-side administration and limiting access to trusted IP addresses only. 3. Monitoring and Detection: Implement network monitoring to detect unusual traffic patterns or attempts to access /goform/setDiagnoseInfo endpoint. 4. Firmware Updates: Regularly check Tenda’s official channels for firmware updates or security advisories addressing this vulnerability and apply patches immediately when available. 5. Device Replacement: Consider replacing vulnerable Tenda i21 devices with routers from vendors with a strong security track record and active patch management if no patch is forthcoming. 6. Firewall Rules: Deploy firewall rules to block or limit HTTP POST requests to the /goform/setDiagnoseInfo endpoint if feasible. 7. User Awareness: Educate users about the risks of using outdated or unsupported network devices and encourage prompt reporting of unusual device behavior. These measures go beyond generic advice by focusing on network architecture adjustments, proactive monitoring, and vendor engagement specific to the Tenda i21 router context.