CVE-2025-7793 is a critical stack-based buffer overflow vulnerability identified in the Tenda FH451 router, specifically affecting firmware version 1.0.0.9. The vulnerability resides in the function formWebTypeLibrary within the /goform/webtypelibrary endpoint. The flaw arises from improper handling of the webSiteId argument, which can be manipulated by an attacker to overflow the stack buffer. This overflow can lead to arbitrary code execution or denial of service conditions. The vulnerability is remotely exploitable without requiring user interaction or authentication, making it highly dangerous. The CVSS 4.0 base score of 8.7 reflects its high severity, with attack vector being network-based, low attack complexity, no privileges or user interaction required, and high impact on confidentiality, integrity, and availability. Although no public exploits are currently known to be actively used in the wild, the exploit code has been disclosed publicly, increasing the risk of exploitation by threat actors. The lack of available patches at the time of disclosure further exacerbates the threat, leaving affected devices vulnerable until firmware updates are released and applied.

For European organizations, the impact of this vulnerability can be significant, especially for enterprises and service providers relying on Tenda FH451 routers for network connectivity. Successful exploitation could allow attackers to gain control over the router, enabling interception or manipulation of network traffic, disruption of internet access, or pivoting into internal networks. This could lead to data breaches, espionage, or operational disruptions. Given the critical role of routers in network infrastructure, compromised devices could also be leveraged in botnets or for launching further attacks such as distributed denial-of-service (DDoS). The vulnerability's remote exploitability without authentication increases the risk of widespread attacks, particularly in environments where these routers are deployed without adequate network segmentation or monitoring. Additionally, the absence of patches means organizations must rely on interim mitigations, increasing exposure time. The impact is heightened for sectors with stringent data protection requirements under GDPR, as any breach could result in regulatory penalties and reputational damage.

Immediate mitigation steps include isolating affected Tenda FH451 devices from untrusted networks and restricting access to the /goform/webtypelibrary endpoint via firewall rules or access control lists to prevent remote exploitation. Network administrators should monitor network traffic for unusual activity indicative of exploitation attempts, such as unexpected requests to the vulnerable endpoint or anomalous router behavior. Employing network segmentation to limit exposure of critical infrastructure devices is advisable. Organizations should engage with Tenda support channels to obtain firmware updates or security advisories and apply patches as soon as they become available. In the interim, disabling remote management features on these routers can reduce attack surface. Additionally, deploying intrusion detection/prevention systems (IDS/IPS) with signatures targeting this vulnerability can help detect and block exploit attempts. Regularly auditing router configurations and maintaining an asset inventory to identify all affected devices is crucial for comprehensive mitigation.