CVE-2025-12213 is a stack-based buffer overflow vulnerability identified in Tenda O3 version 1.0.0.10(2478), affecting the functions SetValue and GetValue within the /goform/setVlanConfig endpoint. The vulnerability arises from improper handling of the 'lan' parameter, which can be manipulated remotely to cause a stack overflow. This type of vulnerability can lead to arbitrary code execution, allowing an attacker to potentially take full control of the affected device. The vulnerability requires no user interaction and no prior authentication, making it highly exploitable over the network. The CVSS 4.0 base score is 8.7, indicating a high severity level due to the ease of exploitation (network attack vector, low complexity), and the significant impact on confidentiality, integrity, and availability. The vulnerability was publicly disclosed shortly after reservation, and while no known exploits are currently active in the wild, the public availability of exploit code increases the likelihood of imminent attacks. Tenda O3 devices are typically used in small office/home office environments, but their compromise could serve as a foothold for lateral movement or network disruption. The lack of available patches at the time of disclosure necessitates immediate mitigation efforts to reduce exposure.

For European organizations, this vulnerability poses a significant risk to network security, especially for those relying on Tenda O3 devices for routing or VLAN management. Successful exploitation could lead to unauthorized remote code execution, allowing attackers to disrupt network operations, intercept or manipulate sensitive data, and potentially pivot to other internal systems. This could impact confidentiality by exposing internal communications, integrity by altering network configurations, and availability by causing device crashes or denial of service. Critical sectors such as finance, healthcare, and government agencies using these devices could face operational disruptions or data breaches. Additionally, the ease of exploitation without authentication increases the threat level, making automated attacks or worm-like propagation feasible. The public disclosure of exploit code further elevates the risk of widespread attacks targeting vulnerable devices across Europe.

Given the absence of an official patch at the time of disclosure, European organizations should implement the following specific mitigations: 1) Immediately disable remote management interfaces on Tenda O3 devices to prevent external exploitation. 2) Restrict network access to the /goform/setVlanConfig endpoint via firewall rules or access control lists, allowing only trusted internal IPs if possible. 3) Segment networks to isolate vulnerable devices from critical infrastructure and sensitive data environments. 4) Monitor network traffic for unusual requests targeting the vulnerable endpoint or anomalous behavior indicative of exploitation attempts. 5) Engage with Tenda support channels to obtain firmware updates or security advisories and apply patches promptly once available. 6) Consider replacing vulnerable devices with alternatives that have a stronger security posture if immediate patching is not feasible. 7) Conduct regular vulnerability scans and penetration tests focusing on network devices to detect similar issues proactively.