CVE-2025-11326 is a stack-based buffer overflow vulnerability identified in the Tenda AC18 router firmware version 15.03.05.19(6318). The vulnerability arises from improper handling of the wifi_chkHz parameter within the /goform/WifiMacFilterSet endpoint. An attacker can remotely send a specially crafted request manipulating this parameter to overflow the stack buffer, potentially overwriting control data such as return addresses. This can lead to arbitrary code execution or cause the device to crash, resulting in denial of service. The vulnerability requires no authentication or user interaction, making it remotely exploitable over the network. The CVSS 4.0 vector indicates network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:L), no user interaction (UI:N), and high impact on confidentiality, integrity, and availability (VC:H/VI:H/VA:H). Although no active exploitation has been reported, the public availability of an exploit increases the likelihood of future attacks. The flaw affects a widely deployed consumer and small business router model, which is often used in home and office environments, potentially exposing many networks to compromise. No official patches or mitigation instructions have been published yet, increasing the urgency for defensive measures.

Successful exploitation of this vulnerability can have severe consequences for affected organizations. Attackers could gain unauthorized control over the router, allowing them to intercept, modify, or redirect network traffic, compromising confidentiality and integrity. They could also disrupt network availability by crashing the device or causing persistent denial of service. Since routers serve as critical network gateways, compromise could facilitate lateral movement into internal networks, enabling further attacks on connected systems. The lack of authentication and user interaction requirements lowers the barrier for attackers, increasing the risk of widespread exploitation. Organizations relying on Tenda AC18 devices, especially in environments with sensitive data or critical infrastructure, face significant operational and security risks if this vulnerability is not addressed promptly.

Given the absence of an official patch, organizations should implement immediate compensating controls. First, restrict access to the router's management interface by limiting exposure to trusted networks only, ideally isolating it from the internet. Employ network segmentation to reduce the impact of a compromised device. Monitor network traffic for unusual activity targeting the /goform/WifiMacFilterSet endpoint or abnormal requests containing the wifi_chkHz parameter. Disable remote management features if not required. If possible, upgrade to a newer firmware version once available or consider replacing affected devices with models from vendors with timely security updates. Additionally, implement intrusion detection/prevention systems (IDS/IPS) with signatures to detect exploitation attempts. Maintain regular backups of router configurations and ensure incident response plans include scenarios involving network device compromise.