CVE-2025-13191 is a stack-based buffer overflow vulnerability identified in the D-Link DIR-816L router, specifically affecting the soapcgi_main function within the /soap.cgi endpoint. This vulnerability arises due to improper handling of input data, allowing an attacker to overflow the stack buffer remotely. The flaw exists in firmware version 2_06_b09_beta, which is no longer supported by the vendor, meaning no official patches or updates are available. The vulnerability can be triggered remotely without requiring authentication or user interaction, making it highly exploitable. Successful exploitation could lead to arbitrary code execution with elevated privileges, potentially allowing attackers to take full control of the device. This could compromise the confidentiality, integrity, and availability of the network traffic passing through the router, and enable lateral movement within the victim's network. The CVSS 4.0 score of 8.7 reflects the vulnerability's high impact and ease of exploitation. Although no active exploits have been reported in the wild, the public disclosure of the vulnerability increases the risk of future attacks. The affected device is commonly used in home and small office environments, but may also be present in some enterprise edge deployments, especially in less frequently updated networks.

For European organizations, the exploitation of CVE-2025-13191 could lead to severe consequences. Compromise of the router could allow attackers to intercept, modify, or redirect network traffic, leading to data breaches or disruption of services. The ability to execute arbitrary code remotely without authentication increases the risk of widespread compromise, especially in networks where these routers are used as gateways or for remote access. The lack of vendor support and patches means organizations cannot rely on official fixes, increasing exposure time. This vulnerability could be leveraged as an entry point for further attacks against internal systems, impacting business continuity and data protection obligations under regulations like GDPR. Small and medium enterprises, as well as home office setups using this device, are particularly vulnerable. Additionally, critical infrastructure or public sector entities using outdated D-Link routers could face operational disruptions or espionage risks.

Given the absence of vendor patches, European organizations should prioritize immediate mitigation steps beyond generic advice. First, identify and inventory all D-Link DIR-816L devices running the vulnerable firmware version. Disable remote management interfaces exposed to the internet to reduce attack surface. Implement strict network segmentation to isolate vulnerable routers from critical internal networks. Where possible, replace affected devices with supported models that receive regular security updates. Employ network-based intrusion detection systems (IDS) to monitor for anomalous traffic targeting /soap.cgi endpoints. Apply strict firewall rules to restrict access to router management ports. Educate users and administrators about the risks of using unsupported firmware and the importance of timely device replacement. Consider deploying virtual private networks (VPNs) or alternative secure remote access solutions instead of relying on vulnerable routers. Finally, maintain up-to-date asset and vulnerability management processes to detect and remediate similar risks proactively.