CVE-2026-3970 is a stack-based buffer overflow vulnerability identified in Tenda i3 router firmware version 1.0.0.6(2204). The vulnerability resides in the formwrlSSIDget function, which processes requests to the /goform/wifiSSIDget endpoint. Specifically, the flaw arises from improper handling of the 'index' argument, which when manipulated, causes a stack buffer overflow. This type of vulnerability can allow an attacker to overwrite the stack memory, potentially leading to arbitrary code execution or denial of service. The vulnerability is remotely exploitable over the network without requiring authentication or user interaction, increasing its risk profile. The CVSS v4.0 score is 8.7 (high), reflecting the ease of exploitation (network vector, low complexity, no privileges or user interaction required) and the high impact on confidentiality, integrity, and availability. Although no confirmed exploits in the wild have been reported, proof-of-concept exploit code has been published, indicating that attackers could weaponize this vulnerability. The affected product, Tenda i3, is a consumer-grade router commonly used in various regions, making the vulnerability relevant to both home users and small businesses. The lack of available patches at the time of disclosure further elevates the urgency for mitigation.

The exploitation of CVE-2026-3970 can have severe consequences for affected organizations and users. Successful exploitation may allow attackers to execute arbitrary code with elevated privileges on the router, leading to full device compromise. This can result in unauthorized network access, interception or manipulation of network traffic, deployment of malware or botnets, and disruption of network services. For organizations, compromised routers can serve as a foothold for lateral movement into internal networks, risking sensitive data exposure and operational disruption. The vulnerability's remote exploitability without authentication increases the attack surface, especially for devices exposed to the internet. Given the widespread use of Tenda routers in residential and small business environments, the potential scale of impact is significant. Additionally, the absence of patches at disclosure time means many devices remain vulnerable, increasing the window of opportunity for attackers.

To mitigate CVE-2026-3970, organizations and users should first check for and apply any firmware updates or patches released by Tenda addressing this vulnerability. If no official patch is available, immediate risk reduction steps include restricting access to the router's management interfaces by disabling remote administration and limiting access to trusted networks only. Network segmentation should be employed to isolate vulnerable devices from critical infrastructure. Employing network-level protections such as firewalls or intrusion prevention systems to detect and block suspicious requests targeting the /goform/wifiSSIDget endpoint can help reduce exposure. Monitoring network traffic for anomalous activity related to this endpoint is advisable. Additionally, consider replacing affected devices with models from vendors with more robust security update practices if timely patches are not forthcoming. Regularly reviewing device configurations and disabling unnecessary services can further reduce attack vectors.