CVE-2026-1744 is a cross-site scripting vulnerability identified in the D-Link DSL-6641K router firmware version N8.TR069.20131126. The vulnerability resides in the JavaScript function doSubmitPPP within the sp_pppoe_user.js file, specifically in the handling of the Username argument. Improper input validation allows an attacker to inject malicious scripts remotely, which can execute in the context of the victim's browser. This XSS flaw can be exploited to perform actions such as session hijacking, credential theft, or unauthorized configuration changes if the victim interacts with a crafted malicious link or page. The attack vector is remote and requires user interaction but does not require authentication, although the CVSS vector indicates a high privilege requirement, suggesting exploitation may be limited to authenticated users with elevated rights. The product affected is no longer supported by D-Link, meaning no official patches or updates are available to remediate this issue. The exploit code has been publicly disclosed, increasing the risk of exploitation despite no confirmed active attacks in the wild. The vulnerability affects only a specific firmware version, limiting the scope to devices still running this legacy software. The CVSS 4.8 score reflects a medium severity, balancing the ease of exploitation with the limited impact on confidentiality and availability. This vulnerability highlights the risks associated with using unsupported network devices, especially in environments where remote management interfaces are exposed. Organizations relying on these routers should consider immediate mitigation steps to reduce exposure.

For European organizations, the impact of CVE-2026-1744 can vary depending on the deployment of the affected D-Link DSL-6641K routers. Successful exploitation of this XSS vulnerability could lead to session hijacking, unauthorized configuration changes, or the execution of malicious scripts within the administrative interface of the router. This could compromise network integrity, potentially allowing attackers to intercept or redirect traffic, degrade network availability, or facilitate further attacks within the internal network. The fact that the device is no longer supported exacerbates the risk, as no patches or vendor support are available to address the vulnerability. Organizations in sectors with critical infrastructure or sensitive data, such as finance, healthcare, or government, may face increased risks if legacy devices remain in use. Additionally, remote exploitation capability means that attackers do not need physical access, increasing the attack surface. However, the requirement for user interaction and high privileges limits the ease of exploitation, somewhat reducing the overall risk. Still, the presence of publicly available exploit code could lead to opportunistic attacks, especially in environments where security hygiene is poor or where remote management interfaces are exposed to the internet.

Given the lack of vendor support and absence of official patches, European organizations should adopt a multi-layered mitigation approach. First, identify and inventory all D-Link DSL-6641K devices running the affected firmware version. Where possible, replace these legacy routers with supported, updated hardware to eliminate the vulnerability entirely. If replacement is not immediately feasible, disable remote management interfaces to reduce exposure to remote attackers. Implement strict network segmentation to isolate legacy devices from critical network segments and sensitive data. Employ web application firewalls (WAFs) or intrusion prevention systems (IPS) capable of detecting and blocking XSS attack patterns targeting router management interfaces. Educate users and administrators about the risks of interacting with suspicious links or emails that could trigger XSS payloads. Regularly monitor network traffic and logs for signs of exploitation attempts. Finally, consider deploying endpoint security solutions that can detect malicious script execution resulting from XSS attacks. These combined measures will reduce the likelihood and impact of exploitation while transitioning away from unsupported hardware.