CVE-2025-7792 is a critical stack-based buffer overflow vulnerability identified in the Tenda FH451 router, specifically affecting version 1.0.0.9. The vulnerability resides in the function formSafeEmailFilter within the /goform/SafeEmailFilter endpoint. An attacker can manipulate the 'page' argument passed to this function, causing a stack-based buffer overflow. This type of vulnerability occurs when more data is written to a buffer located on the stack than it can hold, potentially overwriting adjacent memory and allowing arbitrary code execution. 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 4.0 base score is 8.7, categorizing it as high severity. The vulnerability impacts confidentiality, integrity, and availability (all rated high in the CVSS vector), meaning an attacker could execute arbitrary code, potentially gaining control over the device, intercepting or manipulating network traffic, or causing denial of service. Although no known exploits are currently observed in the wild, the public disclosure of the exploit increases the risk of active exploitation. The lack of available patches or vendor mitigation guidance at the time of publication further elevates the threat level. Given the critical role routers play in network infrastructure, exploitation could serve as a foothold for lateral movement within networks or as a launch point for broader attacks.

For European organizations, the exploitation of this vulnerability in Tenda FH451 routers could have severe consequences. Many small and medium enterprises (SMEs) and some home office setups use Tenda devices due to their cost-effectiveness and ease of deployment. A successful attack could lead to unauthorized access to internal networks, interception of sensitive communications, and disruption of business operations. The compromise of network infrastructure devices like routers can undermine the confidentiality and integrity of corporate data, potentially leading to data breaches and regulatory non-compliance under GDPR. Additionally, compromised routers could be leveraged to launch further attacks such as man-in-the-middle (MITM), malware distribution, or participation in botnets, amplifying the impact beyond the initial target. The remote and unauthenticated nature of the exploit increases the attack surface, making it easier for threat actors to target vulnerable devices across Europe without requiring physical access or user interaction.

Given the absence of official patches at the time of disclosure, European organizations should implement immediate compensating controls. First, network segmentation should be enforced to isolate Tenda FH451 devices from critical assets and sensitive data. Access to the router's management interface should be restricted using firewall rules, allowing only trusted IP addresses to connect. Monitoring network traffic for unusual patterns or spikes can help detect exploitation attempts. Organizations should consider disabling or restricting the vulnerable /goform/SafeEmailFilter endpoint if possible, or applying custom firewall rules to block malicious payloads targeting the 'page' parameter. Regularly updating router firmware is essential once a patch is released. Additionally, organizations should conduct asset inventories to identify all Tenda FH451 devices and prioritize their remediation. Employing intrusion detection/prevention systems (IDS/IPS) with signatures for this vulnerability can provide early warning and automated blocking. Finally, educating IT staff about this vulnerability and encouraging vigilance against unusual router behavior will improve overall security posture.