CVE-2025-7506 is a critical stack-based buffer overflow vulnerability identified in the Tenda FH451 router, specifically version 1.0.0.9. The flaw exists in the HTTP POST request handler component, within the fromNatlimit function located in the /goform/Natlimit endpoint. The vulnerability arises from improper handling of the 'page' argument, which can be manipulated by an attacker to overflow the stack buffer. This overflow can lead to arbitrary code execution or cause the device to crash, resulting in denial of service. The vulnerability is remotely exploitable without requiring user interaction or authentication, making it highly dangerous. The CVSS 4.0 base score is 8.7 (high severity), reflecting the ease of exploitation (network attack vector, low complexity), no privileges required, and no user interaction needed. The impact on confidentiality, integrity, and availability is high, as successful exploitation can allow attackers to execute arbitrary code with the privileges of the HTTP service, potentially leading to full device compromise. Although no public exploits are currently known to be in the wild, the vulnerability has been publicly disclosed, increasing the risk of exploitation by threat actors. No patches or mitigations have been officially released by the vendor at the time of publication, which further elevates the risk for affected users.

For European organizations, the exploitation of this vulnerability could have significant consequences. The Tenda FH451 is a consumer and small office/home office (SOHO) router, which may be used in small businesses and remote offices across Europe. Successful exploitation could allow attackers to gain control over network traffic, intercept sensitive data, or pivot into internal networks, compromising confidentiality and integrity. Additionally, disruption of network availability through denial of service could impact business operations, especially for organizations relying on these devices for critical connectivity. Given the remote exploitability without authentication, attackers could target vulnerable devices en masse, potentially leading to widespread network disruptions or use of compromised routers as part of botnets or other malicious infrastructure. This risk is heightened in environments where network segmentation and device monitoring are limited. The lack of an official patch means organizations must rely on interim mitigations, increasing exposure time.

Immediate mitigation should focus on network-level protections and device hardening. Organizations should: 1) Restrict access to the router's management interface by implementing firewall rules that limit HTTP POST requests to trusted IP addresses only, ideally blocking WAN-side access to the /goform/Natlimit endpoint. 2) Disable remote management features if not required, to reduce the attack surface. 3) Monitor network traffic for unusual POST requests targeting the vulnerable endpoint and implement intrusion detection/prevention system (IDS/IPS) signatures to detect exploitation attempts. 4) Segregate vulnerable devices on isolated network segments to limit lateral movement in case of compromise. 5) Regularly audit and inventory network devices to identify any Tenda FH451 routers running version 1.0.0.9. 6) Engage with Tenda support channels to obtain updates or patches as soon as they become available and plan for prompt deployment. 7) Consider replacing vulnerable devices with models from vendors with a stronger security track record if patching is delayed. These steps go beyond generic advice by focusing on specific controls tailored to the vulnerability's characteristics and the affected product.