CVE-2025-12236 is a buffer overflow vulnerability identified in the Tenda CH22 router firmware version 1.0.0.1. The vulnerability exists in the fromDhcpListClient function within the /goform/DhcpListClient endpoint, where improper handling of the 'page' argument leads to a buffer overflow condition. This flaw allows a remote attacker to send specially crafted requests to the router without requiring authentication or user interaction, triggering the overflow. The consequence of this overflow can be arbitrary code execution, enabling attackers to compromise the device fully, potentially gaining control over network traffic, intercepting data, or launching further attacks within the network. The vulnerability has been assigned a CVSS 4.0 score of 8.7, reflecting its high severity due to the network attack vector, low complexity, no privileges or user interaction required, and high impact on confidentiality, integrity, and availability. Although no known exploits are currently active in the wild, the public disclosure of exploit code increases the likelihood of imminent attacks. The vulnerability affects only firmware version 1.0.0.1, and no official patches have been linked yet, emphasizing the need for vigilance and proactive mitigation by affected users.

For European organizations, the exploitation of CVE-2025-12236 could lead to severe consequences including unauthorized access to internal networks, interception or manipulation of sensitive data, disruption of network services, and potential lateral movement within corporate environments. Given that routers like the Tenda CH22 often serve as the primary gateway for internet connectivity, a compromised device could undermine the confidentiality, integrity, and availability of organizational communications. Critical sectors such as finance, healthcare, manufacturing, and government agencies could face operational disruptions and data breaches. The remote and unauthenticated nature of the exploit increases the risk of widespread attacks, especially if exploit code becomes widely available. Additionally, the lack of current patches means organizations must rely on interim controls, increasing operational complexity and risk exposure.

Organizations should immediately inventory their network infrastructure to identify any Tenda CH22 devices running firmware version 1.0.0.1. Until an official patch is released, network administrators should restrict access to the /goform/DhcpListClient endpoint by implementing firewall rules or access control lists that limit management interface exposure to trusted internal networks only. Network segmentation should be employed to isolate vulnerable devices from critical systems. Monitoring network traffic for unusual requests targeting the vulnerable endpoint can help detect exploitation attempts. Where possible, replace affected devices with updated hardware or firmware versions that are not vulnerable. Engage with Tenda support channels to obtain information on forthcoming patches and apply them promptly once available. Additionally, implement intrusion detection/prevention systems (IDS/IPS) signatures tailored to detect exploitation attempts of this specific vulnerability. Regularly update and audit network device configurations to minimize attack surfaces.