CVE-2025-4896 is a critical buffer overflow vulnerability identified in the Tenda AC10 router, specifically affecting firmware version 16.03.10.13. The vulnerability arises from improper handling of the 'getuid' argument in the /goform/UserCongratulationsExec endpoint. This flaw allows an attacker to manipulate input parameters to overflow a buffer, potentially overwriting adjacent memory and enabling arbitrary code execution. The vulnerability is remotely exploitable without requiring user interaction or prior authentication, increasing its risk profile. The CVSS 4.0 base score of 8.7 reflects high severity, with network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:L), and no user interaction (UI:N). The impact metrics indicate high confidentiality, integrity, and availability impacts, meaning successful exploitation could lead to full compromise of the device. Although no public exploits have been observed in the wild yet, the disclosure of the exploit code increases the likelihood of active exploitation. The Tenda AC10 is a widely used consumer-grade wireless router, and such vulnerabilities can be leveraged to gain persistent access to internal networks, intercept or manipulate traffic, or launch further attacks against connected devices. The absence of an official patch at the time of disclosure further elevates the risk for affected users.

For European organizations, this vulnerability poses significant risks, especially for small and medium enterprises (SMEs) and home office environments that commonly deploy consumer-grade routers like the Tenda AC10. Exploitation could lead to unauthorized network access, data interception, and lateral movement within corporate networks, potentially compromising sensitive information and disrupting business operations. The high impact on confidentiality, integrity, and availability means attackers could exfiltrate data, inject malicious payloads, or cause denial of service conditions. Given the remote exploitability without authentication, attackers can target vulnerable routers over the internet, increasing the attack surface. This is particularly concerning for organizations with remote workers relying on vulnerable routers for VPN or other secure connections. Additionally, compromised routers can be used as a foothold for launching attacks against critical infrastructure or supply chain partners within Europe, amplifying the threat.

Organizations should immediately identify any Tenda AC10 devices running firmware version 16.03.10.13 within their networks. Since no official patch is currently available, interim mitigations include disabling remote management interfaces to prevent external access to the vulnerable endpoint. Network segmentation should be enforced to isolate vulnerable devices from critical assets. Employing intrusion detection/prevention systems (IDS/IPS) with signatures for known exploit attempts targeting this vulnerability can help detect and block attacks. Organizations should monitor network traffic for unusual activity originating from or directed to Tenda AC10 devices. Where possible, replace affected devices with models from vendors providing timely security updates. Additionally, users should change default credentials and ensure strong passwords are set to reduce the risk of exploitation. Regular firmware update checks are essential to apply patches once released. Finally, educating users about the risks of using consumer-grade routers in professional environments can help reduce exposure.