CVE-2025-3996 is a cross-site scripting (XSS) vulnerability identified in the TOTOLINK N150RT router, specifically version 3.4.0-B20190525. The vulnerability resides in the MAC Filtering Page, within the /home.htm file, where the 'Comment' parameter can be manipulated by an attacker to inject malicious scripts. This vulnerability is exploitable remotely without requiring authentication, although it does require user interaction to trigger the malicious payload (e.g., a user visiting a crafted URL or page). The CVSS 4.0 base score is 4.8, indicating a medium severity level. The attack vector is network-based (AV:N), with low attack complexity (AC:L), no privileges required (PR:H indicates high privileges required, but the vector states no privileges needed, so this is a discrepancy; based on the vector, PR:H means privileges required, so the attacker must have high privileges), and user interaction is required (UI:P). The vulnerability impacts confidentiality minimally, with limited impact on integrity and availability. No known exploits are currently observed in the wild, but public disclosure of the exploit code exists, increasing the risk of exploitation. The vulnerability allows an attacker to execute arbitrary scripts in the context of the victim's browser, potentially leading to session hijacking, phishing, or other client-side attacks targeting users managing the router's web interface.

For European organizations using TOTOLINK N150RT routers, this vulnerability poses a moderate risk primarily to network administrators or users who access the router's web management interface. Successful exploitation could lead to theft of administrative credentials, unauthorized configuration changes, or pivoting into internal networks. While the direct impact on large-scale infrastructure is limited due to the medium severity and requirement for user interaction, organizations with less secure network environments or those relying on TOTOLINK devices in sensitive contexts (e.g., small offices, remote sites) could face increased risk of targeted attacks. Additionally, if attackers leverage this XSS vulnerability as part of a broader attack chain, it could facilitate lateral movement or data exfiltration. The risk is heightened in environments where users are less trained to recognize phishing or malicious links, and where routers are not regularly updated or monitored.

1. Immediate mitigation involves updating the firmware of TOTOLINK N150RT devices to a patched version once available from the vendor. Since no patch links are currently provided, organizations should monitor TOTOLINK's official channels for updates. 2. Restrict access to the router's web management interface to trusted IP addresses or internal networks only, using firewall rules or network segmentation to reduce exposure. 3. Disable or limit the use of the MAC Filtering Page or the 'Comment' field if possible, to reduce the attack surface. 4. Implement strict input validation and sanitization on the router's web interface if custom firmware or management tools are used. 5. Educate users and administrators about the risks of clicking on unsolicited links or opening suspicious web pages related to router management. 6. Employ network monitoring to detect unusual access patterns or attempts to exploit the vulnerability. 7. Consider replacing affected devices with models from vendors with stronger security track records if timely patching is not feasible.