CVE-2025-7551 is a critical stack-based buffer overflow vulnerability identified in the Tenda FH1201 router, specifically in firmware version 1.2.0.14(408). The vulnerability resides in the function fromPptpUserAdd within the /goform/PPTPDClient component. This function processes user-supplied input parameters, notably the modino/username argument. Improper validation or sanitization of this input allows an attacker to overflow the stack buffer, potentially overwriting adjacent memory regions. This type of vulnerability can lead to arbitrary code execution, denial of service, or system compromise. The vulnerability is remotely exploitable without requiring user interaction or authentication, as indicated by the CVSS vector (AV:N/AC:L/AT:N/UI:N/PR:L). The CVSS score of 8.7 (high severity) reflects the significant risk posed by this flaw, given the ease of exploitation and the critical nature of the affected device. Although no known exploits are currently reported in the wild, public disclosure of the exploit code increases the likelihood of active exploitation attempts. The Tenda FH1201 is a consumer-grade router commonly used in home and small office environments, which may be deployed in various European countries. The vulnerability affects the confidentiality, integrity, and availability of the device and potentially the entire network it protects, as successful exploitation could allow attackers to execute arbitrary code with elevated privileges, disrupt network connectivity, or intercept sensitive data.

For European organizations, especially small and medium enterprises (SMEs) and residential users relying on Tenda FH1201 routers, this vulnerability poses a significant threat. Exploitation could lead to unauthorized network access, interception of confidential communications, and disruption of internet connectivity. In environments where these routers are used as primary gateways, attackers could pivot to internal networks, compromising additional systems and data. The lack of authentication requirement and remote exploitability means attackers can launch attacks from anywhere, increasing the risk of widespread compromise. Critical sectors such as healthcare, finance, and government entities using these devices in branch offices or remote locations could face operational disruptions and data breaches. Additionally, the vulnerability could be leveraged in botnet campaigns or distributed denial-of-service (DDoS) attacks, amplifying its impact across European networks.

1. Immediate firmware update: Organizations and users should verify if Tenda has released a patched firmware version addressing CVE-2025-7551 and apply it promptly. 2. Network segmentation: Isolate vulnerable routers from critical internal networks to limit potential lateral movement in case of compromise. 3. Disable PPTP client functionality if not required, as the vulnerability is in the PPTP client component. 4. Implement network-level protections such as intrusion detection/prevention systems (IDS/IPS) to monitor and block suspicious traffic targeting the /goform/PPTPDClient endpoint. 5. Restrict remote management access to the router, ideally limiting it to trusted IP addresses or disabling it entirely. 6. Employ strong network perimeter defenses and monitor for unusual outbound traffic that could indicate exploitation attempts. 7. Conduct regular vulnerability assessments and penetration testing focusing on network devices to identify and remediate similar issues proactively.