CVE-2025-4348 is a critical buffer overflow vulnerability identified in the D-Link DIR-600L router firmware version up to 2.07B01. The flaw exists in the function formSetWanL2TP, which processes the 'host' argument. Improper handling of this input allows an attacker to overflow a buffer, potentially leading to arbitrary code execution or denial of service. The vulnerability can be exploited remotely without user interaction or prior authentication, increasing its risk profile. However, this issue affects only legacy devices that are no longer supported by D-Link, meaning no official patches or firmware updates are available. The CVSS 4.0 base score is 8.7 (high), reflecting the ease of remote exploitation and the significant impact on confidentiality, integrity, and availability. Although no known exploits are currently reported in the wild, the vulnerability poses a serious risk if attackers develop exploit code. The lack of vendor support complicates mitigation efforts, as users must rely on network-level protections or device replacement. This vulnerability highlights the risks associated with using outdated network hardware that is no longer maintained or patched.

For European organizations, the exploitation of CVE-2025-4348 could lead to unauthorized remote control over affected D-Link DIR-600L routers, resulting in compromised network integrity and confidentiality. Attackers could intercept, modify, or redirect network traffic, disrupt internet connectivity, or use the compromised devices as footholds for lateral movement within corporate networks. Given that the affected devices are end-of-life and unsupported, organizations relying on them face heightened exposure without vendor patches. This is particularly concerning for small and medium enterprises or home office setups that may still use these routers due to cost constraints. The impact extends to potential data breaches, operational disruptions, and reputational damage. Additionally, compromised routers could be conscripted into botnets, amplifying broader cyber threats. European entities with critical infrastructure or sensitive data are at increased risk if these devices are present in their network perimeters.

Since no official patches are available for the affected firmware version, European organizations should prioritize immediate replacement of D-Link DIR-600L devices with supported and regularly updated hardware. Network segmentation should be employed to isolate legacy routers from sensitive internal systems. Implement strict firewall rules to restrict inbound traffic to router management interfaces, especially blocking access to the vulnerable formSetWanL2TP function endpoint if identifiable. Deploy intrusion detection/prevention systems (IDS/IPS) with signatures or anomaly detection capabilities targeting buffer overflow attempts against these routers. Regularly audit network devices to identify and inventory unsupported hardware. Educate users and IT staff about the risks of using end-of-life devices. If replacement is not immediately feasible, disabling L2TP WAN functionality or limiting its exposure to trusted networks may reduce attack surface. Monitoring network traffic for unusual patterns indicative of exploitation attempts is also recommended.