CVE-2025-4544 is a critical security vulnerability identified in the D-Link DI-8100 router, specifically affecting firmware versions up to 16.07.26A1. The vulnerability arises from a stack-based buffer overflow in the jhttpd component, which is responsible for handling HTTP requests. The flaw is triggered by manipulating certain parameters—def_max, def_time, def_tcp_max, def_tcp_time, def_udp_max, def_udp_time, and def_icmp_max—within the /ddos.asp endpoint. These parameters likely control rate-limiting or denial-of-service mitigation settings. Improper validation or bounds checking of these inputs leads to a buffer overflow on the stack, which can corrupt memory and potentially allow an attacker to execute arbitrary code or cause a denial of service. The attack vector is remote, meaning an attacker can exploit this vulnerability over the network without physical access. However, the attack complexity is rated as high, indicating that exploitation requires significant skill or specific conditions, and no known exploits are currently observed in the wild. The CVSS 4.0 score of 7.5 reflects a high severity, with network attack vector, high attack complexity, no privileges required, no user interaction, and high impact on confidentiality, integrity, and availability. The vulnerability does not require authentication, increasing its risk profile. The absence of a patch link suggests that a fix may not yet be publicly available, emphasizing the need for vigilance and mitigation.

For European organizations, the impact of this vulnerability can be significant, especially for those relying on the D-Link DI-8100 router in their network infrastructure. Successful exploitation could lead to unauthorized remote code execution, allowing attackers to compromise the router, intercept or manipulate network traffic, and potentially pivot to internal systems. This could result in data breaches, service disruptions, or network outages. Given the router’s role in managing traffic and possibly providing security functions like DDoS mitigation, exploitation could degrade network availability or security posture. Critical infrastructure operators, enterprises, and service providers using this device could face operational disruptions and reputational damage. The high attack complexity somewhat reduces the immediate risk but does not eliminate it, especially from skilled threat actors or nation-state adversaries targeting European networks. The lack of known exploits in the wild currently limits active exploitation but also means organizations should proactively address the vulnerability before it becomes weaponized.

Organizations should first inventory their network devices to identify any D-Link DI-8100 routers running firmware versions up to 16.07.26A1. Immediate mitigation steps include isolating affected devices from untrusted networks or restricting access to the /ddos.asp endpoint via firewall rules or network segmentation. Network administrators should monitor traffic for unusual requests targeting the vulnerable parameters and implement intrusion detection signatures if available. Since no official patch link is provided, organizations should engage with D-Link support or authorized vendors to obtain firmware updates or security advisories. If patching is not immediately possible, consider disabling or restricting access to the jhttpd service or the affected endpoint to reduce exposure. Regularly update network device firmware and maintain robust network monitoring to detect exploitation attempts. Additionally, implement strict access controls and network segmentation to limit the impact of any potential compromise.