CVE-2025-44899 is a critical stack overflow vulnerability identified in the Tenda RX3 router firmware version V1.0br_V16.03.13.11. The flaw exists in the web interface endpoint /goform/WifiGuestSet, specifically within the fromSetWifiGusetBasic function. The vulnerability arises due to improper handling and validation of the 'shareSpeed' parameter, which can be manipulated by an unauthenticated remote attacker to trigger a stack overflow condition. This type of vulnerability (CWE-121) typically allows an attacker to overwrite the call stack, potentially leading to arbitrary code execution, denial of service, or system compromise. The CVSS v3.1 base score of 9.8 reflects the high severity, with an attack vector of network (AV:N), no privileges required (PR:N), no user interaction (UI:N), and full impact on confidentiality, integrity, and availability (C:H/I:H/A:H). The vulnerability is exploitable remotely without authentication, making it highly dangerous. Although no known exploits are currently reported in the wild, the critical nature and ease of exploitation suggest that threat actors could develop exploits rapidly. The absence of vendor or product details beyond the Tenda RX3 model and lack of available patches increases the urgency for mitigation and monitoring. The stack overflow in a router's web management interface poses a significant risk as it can lead to complete device takeover, enabling attackers to intercept, manipulate, or disrupt network traffic and potentially pivot into connected internal networks.

For European organizations, this vulnerability presents a substantial risk, especially for enterprises and service providers relying on Tenda RX3 routers or similar devices in their network infrastructure. Successful exploitation could result in full compromise of the router, leading to interception of sensitive data, disruption of network services, and lateral movement within corporate networks. This could impact confidentiality through data leakage, integrity by altering network configurations or traffic, and availability by causing device crashes or network outages. Small and medium-sized enterprises (SMEs) and home office setups using these routers are particularly vulnerable due to typically weaker security postures and delayed patching. Additionally, critical infrastructure sectors such as telecommunications, finance, and government agencies using these devices could face severe operational disruptions and espionage risks. The lack of authentication and user interaction requirements means attackers can launch attacks remotely and stealthily, increasing the threat surface. Given the high CVSS score and critical severity, the potential impact on European organizations is significant, warranting immediate attention.

1. Immediate network segmentation: Isolate Tenda RX3 routers from critical internal networks to limit potential lateral movement in case of compromise. 2. Disable remote management interfaces or restrict access to trusted IP addresses only, reducing exposure to external attackers. 3. Monitor network traffic for unusual activity targeting the /goform/WifiGuestSet endpoint or anomalous HTTP requests containing the 'shareSpeed' parameter. 4. Apply strict input validation and filtering at network perimeter devices or web application firewalls (WAFs) to detect and block malformed requests exploiting this vulnerability. 5. Engage with Tenda support or vendors to obtain firmware updates or patches; if unavailable, consider replacing vulnerable devices with models from vendors providing timely security updates. 6. Conduct regular vulnerability scanning and penetration testing focusing on network devices to identify and remediate similar issues proactively. 7. Educate IT staff on the risks of unmanaged IoT and network devices and enforce asset inventory and patch management policies. 8. Implement intrusion detection/prevention systems (IDS/IPS) signatures tailored to detect exploitation attempts targeting this vulnerability.