CVE-2025-28019 is a buffer overflow vulnerability identified in the TOTOLINK A800R router firmware version 4.1.2cu.5137_B20200730, specifically within the downloadFile.cgi component. 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, crashes, or other unpredictable behavior. The affected component, downloadFile.cgi, is likely a CGI script responsible for handling file download requests on the device. Given that the CVSS vector indicates no privileges required (PR:N), no user interaction (UI:N), and network attack vector (AV:N), this vulnerability can be exploited remotely over the network without authentication or user involvement. The CVSS score of 7.3 (high severity) reflects the potential for an attacker to impact confidentiality, integrity, and availability, albeit with limited confidentiality and integrity impact (C:L/I:L) and limited availability impact (A:L). The vulnerability is classified under CWE-120, which corresponds to classic buffer overflow issues. No known exploits are currently reported in the wild, and no patches have been linked yet, indicating that the vulnerability is either newly disclosed or not yet widely exploited. The vulnerability was reserved in March 2025 and published in April 2025, suggesting recent discovery. TOTOLINK A800R is a consumer-grade wireless router, and the presence of this vulnerability in its firmware could allow attackers to execute arbitrary code remotely, potentially taking full control of the device, intercepting or manipulating network traffic, or causing denial of service conditions. The lack of vendor or product details beyond the model and firmware version limits the scope of precise technical details but does not diminish the criticality of the buffer overflow in a network-facing component.

For European organizations, the impact of this vulnerability can be significant, especially for small and medium enterprises (SMEs) and home office environments that rely on TOTOLINK A800R routers for internet connectivity. Exploitation could lead to unauthorized remote code execution, allowing attackers to compromise the router, intercept or manipulate network traffic, launch further attacks inside the network, or disrupt internet access. This could result in data breaches, loss of sensitive information, operational downtime, and reputational damage. Critical infrastructure or organizations with less mature network security practices that use these routers as part of their network perimeter are particularly at risk. Additionally, compromised routers could be conscripted into botnets, amplifying the threat landscape. Given the router’s consumer-grade nature, many devices may be deployed with default or weak configurations, increasing the likelihood of successful exploitation. The absence of authentication and user interaction requirements further exacerbates the risk, enabling attackers to target vulnerable devices en masse. However, the limited confidentiality and integrity impact rating suggests that while attackers can execute code, the scope of data exposure or manipulation might be constrained by the device’s role and capabilities.

1. Immediate network segmentation: Isolate TOTOLINK A800R devices from critical internal networks to limit potential lateral movement if compromised. 2. Monitor network traffic for unusual activity originating from or targeting TOTOLINK A800R devices, focusing on suspicious requests to the downloadFile.cgi endpoint. 3. Disable or restrict access to the downloadFile.cgi component if possible, or block access to the router’s management interfaces from untrusted networks, especially the internet. 4. Implement strict firewall rules to limit inbound traffic to the router’s management ports, allowing only trusted IP addresses where feasible. 5. Regularly audit and update router firmware; although no patch is currently linked, monitor TOTOLINK’s official channels for updates addressing this vulnerability. 6. Replace or upgrade vulnerable devices in high-risk environments if patches are unavailable or delayed. 7. Employ intrusion detection/prevention systems (IDS/IPS) with signatures or anomaly detection tuned to detect exploitation attempts targeting buffer overflow patterns in CGI scripts. 8. Educate users and administrators about the risks of using consumer-grade routers in enterprise or critical environments and encourage use of enterprise-grade equipment with robust security features.