CVE-2025-7420 is a critical stack-based buffer overflow vulnerability identified in the Tenda O3V2 wireless device, specifically version 1.0.0.12(3880). The flaw resides in the HTTP daemon component (httpd), within the function formWifiBasicSet, which processes requests to the /goform/setWrlBasicInfo endpoint. The vulnerability is triggered by manipulating the extChannel argument in the HTTP request. Improper handling of this argument leads to a stack-based buffer overflow condition, allowing an attacker to overwrite memory on the stack. This can result in arbitrary code execution, denial of service, or system compromise. The vulnerability can be exploited remotely over the network without requiring user interaction or prior authentication, making it highly accessible to attackers. The CVSS v4.0 base score is 8.7 (high severity), reflecting the ease of exploitation (network vector, low complexity), no privileges or user interaction needed, 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 imminent exploitation. No official patches or mitigations have been published by the vendor at this time, which leaves affected devices vulnerable. Given that Tenda O3V2 devices are typically used in wireless networking environments, successful exploitation could allow attackers to gain control over network traffic, intercept sensitive data, or pivot to other internal systems.

For European organizations, this vulnerability poses a significant risk, especially for enterprises, ISPs, and critical infrastructure providers that deploy Tenda O3V2 devices in their network environments. Exploitation could lead to unauthorized access to internal networks, interception or manipulation of sensitive communications, and potential disruption of network services. This is particularly concerning for sectors handling sensitive personal data under GDPR regulations, as a breach could result in data loss and regulatory penalties. Additionally, compromised devices could be leveraged as entry points for broader attacks, including lateral movement within corporate networks or launching further attacks against connected systems. The lack of authentication and user interaction requirements means attackers can target these devices remotely and at scale, increasing the threat surface. The potential for denial of service could also impact availability of network connectivity, affecting business continuity. Organizations relying on Tenda O3V2 for wireless connectivity should consider the vulnerability a high priority for remediation to maintain network security and compliance.

Given the absence of official patches, European organizations should implement immediate compensating controls. First, isolate Tenda O3V2 devices from direct exposure to untrusted networks by placing them behind firewalls or network segmentation controls that restrict access to the /goform/setWrlBasicInfo endpoint. Employ strict network access control lists (ACLs) to limit which IP addresses can communicate with these devices, ideally restricting to trusted management stations only. Monitor network traffic for anomalous HTTP requests targeting the vulnerable endpoint, using intrusion detection/prevention systems (IDS/IPS) with custom signatures to detect exploitation attempts. Disable or restrict remote management interfaces if not required. Where possible, replace vulnerable Tenda O3V2 devices with updated hardware or alternative products from vendors with timely security support. Maintain an inventory of affected devices and track vendor advisories for patches or firmware updates. Additionally, implement network segmentation to limit the impact of a compromised device and ensure robust logging and alerting to detect suspicious activity early. Educate network administrators about the vulnerability and signs of exploitation to enhance incident response readiness.