CVE-2025-12225 is a stack-based buffer overflow vulnerability identified in the Tenda AC6 router firmware version 15.03.06.50. The flaw exists in the HTTP request handler component, specifically in the processing of the shareSpeed parameter within the /goform/WifiGuestSet endpoint. An attacker can remotely send a crafted HTTP request with a manipulated shareSpeed argument that overflows the stack buffer, potentially overwriting critical memory regions. This can lead to arbitrary code execution with elevated privileges on the device, allowing attackers to take full control of the router. The vulnerability requires no authentication or user interaction, making it highly exploitable over the network. The CVSS v4.0 score is 8.7 (high), reflecting the vulnerability's network attack vector, low attack complexity, no privileges required, and high impact on confidentiality, integrity, and availability. Although no exploits have been observed in the wild yet, the public disclosure of the vulnerability increases the likelihood of exploitation attempts. The affected product, Tenda AC6, is a widely used consumer and small business router, often deployed in home and small office networks. The lack of an official patch or mitigation guidance at the time of disclosure necessitates immediate defensive measures to reduce risk.

For European organizations, the exploitation of CVE-2025-12225 could lead to complete compromise of affected Tenda AC6 routers, resulting in unauthorized network access, interception or manipulation of network traffic, and potential pivoting to internal systems. This threatens the confidentiality of sensitive data, the integrity of network communications, and the availability of network services. Small and medium enterprises (SMEs) and home office users relying on these routers are particularly vulnerable due to typically weaker network segmentation and security controls. The compromise of routers can also facilitate large-scale attacks such as botnet recruitment or man-in-the-middle attacks targeting European businesses and consumers. Given the remote, unauthenticated nature of the exploit, attackers can operate stealthily and at scale, increasing the risk of widespread impact across Europe.

1. Immediately isolate affected Tenda AC6 devices from critical network segments to limit exposure. 2. Disable the guest Wi-Fi feature if it is not required, as the vulnerability is triggered via the WifiGuestSet endpoint. 3. Implement network-level filtering to block HTTP requests targeting /goform/WifiGuestSet or suspicious shareSpeed parameter values. 4. Monitor network traffic and device logs for unusual HTTP requests or signs of exploitation attempts. 5. Where possible, replace affected devices with routers from vendors with timely security updates. 6. Engage with Tenda support channels to obtain firmware updates or official patches as they become available. 7. Educate users on the risks of using outdated router firmware and encourage regular updates. 8. Employ network segmentation and zero-trust principles to minimize the impact of compromised devices. 9. Use intrusion detection/prevention systems (IDS/IPS) tuned to detect exploitation attempts targeting this vulnerability.