CVE-2025-11524 is a stack-based buffer overflow vulnerability identified in the Tenda AC7 router firmware version 15.03.06.44. The vulnerability arises from improper handling of the 'ddnsEn' parameter in the HTTP request sent to the /goform/SetDDNSCfg endpoint. Specifically, the parameter manipulation leads to a stack buffer overflow, which can be exploited remotely without requiring authentication or user interaction. This flaw allows an attacker to overwrite the stack, potentially enabling arbitrary code execution with the privileges of the router's web service process. Given the router's role as a network gateway, successful exploitation can compromise network traffic confidentiality and integrity, disrupt availability, or facilitate lateral movement within the network. The CVSS 4.0 base score is 8.7, reflecting high severity due to network attack vector, low attack complexity, no privileges or user interaction required, and high impact on confidentiality, integrity, and availability. Although no active exploitation has been reported, a public exploit is available, increasing the likelihood of future attacks. The vulnerability affects only firmware version 15.03.06.44, so other versions may not be impacted. The lack of an official patch link suggests that users must monitor vendor advisories closely or implement interim mitigations. This vulnerability is particularly concerning for environments where Tenda AC7 routers are deployed as primary network devices, including small businesses and home offices, which may lack robust security controls.

For European organizations, this vulnerability poses a significant risk to network security and operational continuity. Exploitation can lead to full compromise of the affected router, enabling attackers to intercept or manipulate network traffic, deploy malware, or pivot to internal systems. This is especially critical for organizations relying on Tenda AC7 routers in sensitive environments such as SMEs, remote offices, or critical infrastructure sectors where these devices are used as primary gateways. The compromise could result in data breaches, service disruptions, or unauthorized access to internal networks. Given the router's role in managing dynamic DNS configurations, attackers might also manipulate DNS settings to redirect traffic to malicious sites, increasing phishing or malware risks. The availability of a public exploit raises the urgency for European entities to act swiftly to prevent exploitation. Additionally, the absence of user interaction or authentication requirements lowers the barrier for attackers, increasing the threat landscape. The impact extends beyond individual organizations to potentially affect supply chains and connected partners if compromised routers serve as network entry points.

1. Immediate firmware upgrade: Organizations should verify if Tenda has released a patched firmware version beyond 15.03.06.44 and apply it promptly. 2. Network segmentation: Isolate Tenda AC7 routers from critical internal networks to limit potential lateral movement if compromised. 3. Disable remote management: If remote access to the router's management interface is enabled, disable it or restrict it to trusted IP addresses. 4. Monitor network traffic: Implement IDS/IPS solutions to detect anomalous traffic patterns targeting /goform/SetDDNSCfg or unusual DNS configuration changes. 5. Employ web application firewalls (WAFs): Use WAFs to filter and block malicious HTTP requests attempting to exploit the ddnsEn parameter. 6. Replace vulnerable devices: For high-risk environments, consider replacing Tenda AC7 routers with devices from vendors with active security support. 7. User awareness: Educate network administrators about the vulnerability and signs of exploitation to enable rapid incident response. 8. Regular audits: Conduct periodic security assessments of network devices to identify and remediate outdated firmware or configurations. These measures collectively reduce the risk of exploitation while awaiting official patches or device replacement.