CVE-2025-13190 is a stack-based buffer overflow vulnerability identified in the D-Link DIR-816L router firmware version 2_06_b09_beta. The vulnerability resides in the scandir_main function of the /portal/__ajax_exporer.sgi script, where the 'en' argument is improperly validated, allowing an attacker to overflow the stack buffer. This flaw can be exploited remotely without authentication or user interaction, enabling attackers to execute arbitrary code on the device with elevated privileges. The buffer overflow can compromise the device's confidentiality, integrity, and availability by allowing full control over the router. The vulnerability affects only an outdated and unsupported firmware version, meaning no official patches or updates are available from D-Link. Public exploit code has been released, increasing the likelihood of exploitation in the wild. The CVSS 4.0 base score is 8.7, indicating a high-severity issue with network attack vector, low attack complexity, no privileges required, and no user interaction needed. The vulnerability does not require special conditions or physical access, making it a critical risk for exposed devices. The affected router model is commonly used in home and small business environments, which may serve as a pivot point for attackers targeting internal networks. Due to the lack of vendor support, mitigation relies on network-level controls and device replacement.

For European organizations, especially small and medium enterprises or home offices using the D-Link DIR-816L router with the vulnerable firmware, this vulnerability poses a significant risk. Successful exploitation can lead to complete compromise of the router, allowing attackers to intercept, manipulate, or redirect network traffic, deploy malware, or establish persistent footholds within internal networks. This can result in data breaches, disruption of business operations, and potential lateral movement to more critical systems. The lack of vendor support means organizations cannot rely on firmware updates to remediate the issue, increasing exposure duration. Critical infrastructure or organizations with remote workforces using vulnerable devices may face heightened risks. Additionally, the public availability of exploit code lowers the barrier for attackers, including cybercriminals and state-sponsored actors, to weaponize this vulnerability. The impact extends beyond confidentiality to integrity and availability, potentially causing denial of service or network outages.

Given the absence of official patches for the affected firmware, European organizations should prioritize the following mitigations: 1) Immediate replacement of D-Link DIR-816L devices running the vulnerable firmware with updated, supported hardware to eliminate the vulnerability vector. 2) If replacement is not immediately feasible, isolate affected routers from direct internet exposure by placing them behind secure firewalls or VPNs to restrict access to the vulnerable service. 3) Implement strict network segmentation to limit the router's access to critical internal resources and reduce the attack surface. 4) Monitor network traffic for unusual patterns or signs of exploitation attempts targeting the /portal/__ajax_exporer.sgi endpoint. 5) Disable or restrict access to the vulnerable web interface if possible, or employ web application firewalls (WAFs) to detect and block exploit attempts. 6) Educate users about the risks of using unsupported firmware and encourage timely hardware upgrades. 7) Maintain up-to-date asset inventories to identify and track vulnerable devices. 8) Employ intrusion detection/prevention systems (IDS/IPS) tuned to detect exploitation attempts of this CVE. These targeted steps go beyond generic advice by focusing on compensating controls and proactive device management.