CVE-2025-7747 is a critical buffer overflow vulnerability identified in the Tenda FH451 router, specifically version 1.0.0.9. The flaw exists in the POST request handler component, within the function fromWizardHandle located in the /goform/WizardHandle endpoint. The vulnerability arises from improper handling of the PPW argument, which can be manipulated by an attacker to overflow the buffer. This overflow can lead to arbitrary code execution or cause the device to crash, resulting in denial of service. The attack vector is remote and does not require user interaction or prior authentication, making exploitation relatively straightforward. The CVSS 4.0 base score is 8.7, indicating a high severity level with network attack vector, low attack complexity, no privileges required, no user interaction, and high impact on confidentiality, integrity, and availability. Although no public exploits are currently known to be actively used in the wild, the vulnerability has been publicly disclosed, increasing the risk of exploitation by threat actors. The absence of an official patch at the time of disclosure further elevates the risk for affected users. Given the router’s role as a network gateway device, successful exploitation could allow attackers to gain control over the device, intercept or manipulate network traffic, or pivot to internal networks, posing significant security risks to organizations relying on this hardware.

For European organizations, the impact of this vulnerability can be substantial. The Tenda FH451 router is commonly used in small to medium-sized enterprise environments and home office setups. Exploitation could lead to unauthorized access to internal networks, data interception, or disruption of network services, affecting business continuity and data confidentiality. Given the router’s position at the network perimeter, attackers could leverage this vulnerability to establish persistent footholds or launch further attacks within corporate networks. This is particularly concerning for organizations handling sensitive personal data under GDPR regulations, as a breach could lead to regulatory penalties and reputational damage. Additionally, disruption of network availability could impact critical business operations, especially for sectors relying on continuous connectivity such as finance, healthcare, and manufacturing. The remote and unauthenticated nature of the exploit increases the likelihood of automated scanning and exploitation attempts, raising the urgency for mitigation in European contexts where such routers are deployed.

Organizations should immediately inventory their network devices to identify any Tenda FH451 routers running version 1.0.0.9. Until an official patch is released, it is recommended to restrict access to the router’s management interface by implementing network segmentation and firewall rules that limit inbound traffic to trusted IP addresses only. Disabling remote management features and changing default credentials can reduce exposure. Monitoring network traffic for unusual POST requests to /goform/WizardHandle and implementing intrusion detection/prevention systems (IDS/IPS) with signatures targeting this vulnerability can help detect and block exploitation attempts. Organizations should also engage with Tenda support channels to obtain updates on patch availability and apply firmware updates promptly once released. As a longer-term measure, consider replacing vulnerable devices with models that have a stronger security track record and support timely updates. Regular security audits and vulnerability assessments should include checks for this and similar vulnerabilities to maintain a robust security posture.