The vulnerability identified as CVE-2025-51281 affects the D-Link DI-8100 router firmware version 16.07.26A1. It is a buffer overflow vulnerability located in the qj_asp function, specifically triggered by the parameters 'en', 'val', and 'id'. An authenticated attacker can exploit this vulnerability by sending crafted HTTP GET requests with excessively long values for these parameters. The buffer overflow condition can cause the device to crash or become unresponsive, resulting in a Denial of Service (DoS) condition. Since the attack requires authentication, the attacker must have valid credentials or otherwise bypass authentication mechanisms to exploit this flaw. No public exploits or patches are currently known or available, and no CVSS score has been assigned yet. The vulnerability impacts the availability of the device by causing it to stop functioning correctly, potentially disrupting network connectivity for users relying on the affected router. The lack of patch information suggests that mitigation may currently rely on workaround or access control measures. The vulnerability does not appear to allow remote code execution or data disclosure, focusing the impact primarily on service disruption.

For European organizations, the impact of this vulnerability could be significant in environments where the D-Link DI-8100 router is deployed, especially in small to medium-sized enterprises or branch offices that rely on this device for network connectivity. A successful DoS attack could interrupt internet access or internal network communications, leading to operational downtime and productivity loss. Critical services dependent on continuous network availability could be affected, including VoIP, cloud applications, and remote work infrastructure. Since exploitation requires authentication, insider threats or compromised credentials pose a higher risk. The disruption could also affect managed service providers or ISPs using this hardware in their infrastructure. Given the potential for targeted attacks, organizations with sensitive operations or those in sectors such as finance, healthcare, or government could face increased risk. Additionally, the lack of a patch or workaround increases the urgency for organizations to implement compensating controls to prevent exploitation.

Organizations should first inventory their network devices to identify any D-Link DI-8100 routers running firmware version 16.07.26A1. Until a vendor patch is released, it is critical to restrict administrative access to these devices to trusted personnel only, using strong authentication methods such as multi-factor authentication. Network segmentation should be employed to isolate management interfaces from general user networks and the internet. Monitoring and alerting on unusual or repeated HTTP GET requests targeting the 'en', 'val', and 'id' parameters can help detect attempted exploitation. Implementing strict access control lists (ACLs) to limit which IP addresses can reach the router's management interface will reduce exposure. Regularly updating credentials and auditing access logs can help detect and prevent insider threats. If possible, consider replacing affected devices with newer, supported hardware. Finally, maintain communication with D-Link for any forthcoming patches or advisories and apply updates promptly once available.