CVE-2025-5790 is a critical buffer overflow vulnerability identified in the TOTOLINK X15 router firmware version 1.0.0-B20230714.1105. The vulnerability exists in the HTTP POST request handler component, specifically in the /boafrm/formIpQoS endpoint. An attacker can remotely exploit this flaw by manipulating the 'mac' argument in the POST request, causing a buffer overflow. This type of vulnerability can lead to arbitrary code execution, denial of service, or system compromise without requiring user interaction or prior authentication. The CVSS 4.0 score of 8.7 reflects a high severity, with network attack vector, low attack complexity, no privileges required, and no user interaction needed. The vulnerability impacts the confidentiality, integrity, and availability of the device, as successful exploitation could allow an attacker to execute arbitrary code with elevated privileges, potentially taking full control of the router. While no public exploits are currently known in the wild, the disclosure of the exploit details increases the risk of active exploitation. The lack of available patches at the time of publication further elevates the threat level for affected users.

For European organizations, the TOTOLINK X15 router is often deployed in small to medium business environments and residential settings due to its cost-effectiveness and feature set. Exploitation of this vulnerability could lead to network compromise, interception of sensitive communications, and disruption of internet connectivity. Attackers could leverage compromised routers as footholds for lateral movement into corporate networks or as part of botnets for broader attacks. The impact is particularly severe for organizations relying on these devices for perimeter security or VPN termination. Confidentiality breaches could expose sensitive business data, while integrity and availability impacts could disrupt business operations. Given the remote and unauthenticated nature of the exploit, attackers can target vulnerable devices en masse, increasing the risk of widespread impact across European enterprises and home users alike.

Organizations should immediately identify any TOTOLINK X15 devices running the vulnerable firmware version 1.0.0-B20230714.1105. Since no official patches are currently available, temporary mitigations include disabling remote management interfaces and restricting HTTP POST access to the /boafrm/formIpQoS endpoint via firewall rules or access control lists. Network segmentation should be enforced to isolate vulnerable devices from critical infrastructure. Monitoring network traffic for unusual POST requests targeting the affected endpoint can help detect exploitation attempts. Additionally, organizations should engage with TOTOLINK support channels to obtain firmware updates or advisories and plan for prompt firmware upgrades once patches are released. Employing intrusion detection/prevention systems with updated signatures for this vulnerability can further reduce risk.