CVE-2025-45863 is a critical buffer overflow vulnerability identified in the TOTOLINK A3002R router firmware version 4.0.0-B20230531.1404. The vulnerability exists in the formMapDelDevice interface, specifically via the macstr parameter. Buffer overflow vulnerabilities occur when a program writes more data to a buffer than it can hold, potentially overwriting adjacent memory. This can lead to arbitrary code execution, system crashes, or other unpredictable behavior. In this case, the vulnerability allows an unauthenticated remote attacker to send specially crafted requests to the router's interface, exploiting the macstr parameter to trigger the overflow. The CVSS v3.1 base score is 9.8, indicating a critical severity with the following vector: Network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), unchanged scope (S:U), and high impact on confidentiality (C:H), integrity (I:H), and availability (A:H). This means an attacker can fully compromise the device remotely without any authentication or user interaction. The vulnerability is classified under CWE-120 (Classic Buffer Overflow). Currently, there are no known exploits in the wild, and no patches have been published yet. However, given the critical nature and ease of exploitation, this vulnerability poses a significant risk to affected devices. TOTOLINK A3002R is a consumer and small office/home office (SOHO) router model, commonly used for internet connectivity and network management. Exploitation could allow attackers to gain full control over the router, intercept or manipulate network traffic, launch further attacks on connected devices, or disrupt network availability.

For European organizations, especially small and medium enterprises (SMEs) and home users relying on TOTOLINK A3002R routers, this vulnerability presents a severe risk. Compromise of these routers can lead to unauthorized access to internal networks, interception of sensitive communications, and potential lateral movement to other systems. The high impact on confidentiality, integrity, and availability means attackers could steal data, inject malicious content, or cause denial of service. This is particularly concerning for organizations handling personal data under GDPR, as breaches could lead to regulatory penalties and reputational damage. Additionally, compromised routers could be used as a foothold for launching attacks against critical infrastructure or supply chain partners within Europe. The lack of authentication and user interaction requirements lowers the barrier for exploitation, increasing the likelihood of automated attacks or wormable exploits targeting vulnerable devices across European networks.

Given the absence of an official patch, European organizations and users should take immediate steps to mitigate risk. First, identify and inventory all TOTOLINK A3002R routers in use. Restrict remote management interfaces to trusted networks only, ideally disabling WAN-side access to the router's management interface. Implement network segmentation to isolate vulnerable devices from critical systems. Employ intrusion detection and prevention systems (IDS/IPS) to monitor for anomalous traffic patterns targeting the macstr parameter or formMapDelDevice interface. Regularly update router firmware when the vendor releases a patch addressing this vulnerability. In the interim, consider replacing vulnerable routers with models from vendors with a stronger security track record. Educate users about the risks of using outdated or unsupported network devices. Finally, monitor threat intelligence feeds for any emerging exploits or indicators of compromise related to CVE-2025-45863.