CVE-2025-11120 is a high-severity remote buffer overflow vulnerability affecting the Tenda AC8 router, specifically version 16.03.34.06. The vulnerability exists in the function formSetServerConfig within the /goform/SetServerConfig endpoint. This function improperly handles input data, allowing an attacker to craft a malicious request that causes a buffer overflow condition. Buffer overflows can lead to arbitrary code execution, denial of service, or system crashes. The vulnerability can be exploited remotely without user interaction or authentication, as indicated by the CVSS vector (AV:N/AC:L/AT:N/UI:N/PR:L). The exploit complexity is low, and the impact on confidentiality, integrity, and availability is high. Although no patches have been linked yet, the exploit code has been publicly released, increasing the risk of exploitation. The vulnerability does not require user interaction but does require low privileges (PR:L), which may mean an attacker needs some limited access or can exploit it via a network vector that requires minimal privileges. The vulnerability is critical for network security as it targets a widely used consumer and small business router model, potentially allowing attackers to gain control over the device and pivot into internal networks or disrupt connectivity.

For European organizations, this vulnerability poses a significant risk, especially for small and medium enterprises (SMEs) and home office environments that commonly deploy Tenda AC8 routers due to their affordability and ease of use. Exploitation could lead to unauthorized access to internal networks, interception or manipulation of sensitive data, disruption of business operations due to denial of service, and potential lateral movement by attackers within corporate networks. Given the router’s role as a network gateway, compromise could undermine network perimeter defenses and expose connected devices to further attacks. The public availability of exploit code increases the likelihood of opportunistic attacks and automated scanning campaigns targeting vulnerable devices across Europe. Organizations lacking robust network segmentation or monitoring may be particularly vulnerable to stealthy intrusions or persistent threats leveraging this vulnerability.

1. Immediate identification and inventory of all Tenda AC8 routers running firmware version 16.03.34.06 within the organization’s network. 2. Monitor vendor channels and security advisories for official patches or firmware updates addressing CVE-2025-11120 and apply them promptly once available. 3. In the absence of patches, implement network-level mitigations such as restricting access to the router’s management interface to trusted IP addresses only, ideally via VPN or internal network segments. 4. Disable remote management features if not strictly necessary to reduce the attack surface. 5. Employ intrusion detection/prevention systems (IDS/IPS) with signatures or heuristics capable of detecting exploitation attempts targeting /goform/SetServerConfig or anomalous buffer overflow patterns. 6. Conduct regular network traffic monitoring and anomaly detection to identify unusual outbound connections or device behavior indicative of compromise. 7. Educate IT staff and users on the risks and signs of router compromise to enable rapid incident response. 8. Consider network segmentation to isolate critical systems from devices connected via vulnerable routers to limit potential lateral movement.