CVE-2025-65223 is a buffer overflow vulnerability identified in the Tenda AC21 router firmware version V16.03.08.16. The vulnerability resides in the handling of the 'urls' parameter within the /goform/saveParentControlInfo endpoint. Buffer overflow occurs when the input data exceeds the allocated memory buffer, leading to memory corruption. This can potentially allow an attacker to overwrite critical memory regions, resulting in arbitrary code execution or a denial of service (DoS) condition. The vulnerability is triggered by sending a specially crafted HTTP request to the affected endpoint. No authentication requirements or user interaction details are specified, which may imply that exploitation could be possible remotely if the management interface is exposed. Currently, there are no known public exploits or patches available, and the vulnerability was published on November 20, 2025. The lack of a CVSS score necessitates an independent severity assessment based on the nature of the flaw and its potential impact on confidentiality, integrity, and availability. Given that routers are critical network infrastructure devices, compromising them can lead to significant network disruption and unauthorized access to internal networks. The absence of patch links suggests that vendors have not yet released a fix, increasing the urgency for network administrators to implement interim protective measures.

The impact of CVE-2025-65223 on European organizations can be substantial, especially for small and medium-sized enterprises (SMEs) and home office users relying on Tenda AC21 routers. Successful exploitation could allow attackers to execute arbitrary code on the router, potentially gaining control over network traffic, intercepting sensitive data, or launching further attacks within the internal network. This compromises confidentiality and integrity of organizational data and can disrupt availability by causing router crashes or network outages. Given the router's role as a gateway device, attackers could establish persistent footholds or pivot to other critical systems. The lack of known exploits reduces immediate risk but does not eliminate the threat, as proof-of-concept exploits may emerge. European organizations with exposed or poorly secured router management interfaces are particularly vulnerable. The impact is heightened in countries with widespread Tenda router usage and significant reliance on remote or hybrid work environments, where secure network access is critical.

To mitigate CVE-2025-65223, European organizations should take the following specific actions: 1) Monitor Tenda's official channels for firmware updates addressing this vulnerability and apply patches promptly once available. 2) Restrict access to router management interfaces by limiting exposure to trusted internal networks only, using firewall rules or VPNs. 3) Disable remote management features if not required to reduce attack surface. 4) Implement network segmentation to isolate critical systems from potentially compromised devices. 5) Conduct regular network traffic analysis to detect anomalous requests targeting the /goform/saveParentControlInfo endpoint or unusual patterns indicative of exploitation attempts. 6) Educate users and administrators about the risks of exposing router interfaces and encourage strong authentication mechanisms where possible. 7) Consider replacing vulnerable devices with models from vendors with robust security update practices if patches are delayed. These measures go beyond generic advice by focusing on access control, monitoring, and proactive device management tailored to this specific vulnerability.