The CVE-2025-63462 vulnerability is a stack overflow issue identified in the Totolink A7000R router firmware version 9.1.0u.6115_B20201022. The vulnerability arises from improper handling of the wifiOff parameter in the sub_421A04 function, which processes incoming requests. By crafting a specially designed request targeting this parameter, an attacker can overflow the stack, causing the router to crash or reboot, resulting in a Denial of Service (DoS). This type of vulnerability typically stems from insufficient input validation or bounds checking, allowing memory corruption. The attack vector is network-based, requiring the attacker to send malicious requests to the router's management interface, which may be accessible locally or remotely depending on the device configuration. No authentication is required, increasing the risk if the interface is exposed. Currently, there are no known exploits in the wild, and no official patches or firmware updates have been released to address this issue. The vulnerability affects the availability of the device, potentially disrupting network services dependent on the router. Since the affected version is specific, organizations using this firmware version are at risk. The lack of a CVSS score necessitates an assessment based on impact and exploitability factors.

For European organizations, exploitation of this vulnerability could lead to temporary or prolonged network outages due to router crashes, impacting business operations reliant on continuous internet connectivity. Critical sectors such as finance, healthcare, and government services could experience service disruptions, affecting productivity and potentially leading to financial losses or safety risks. The vulnerability affects the availability of network infrastructure rather than confidentiality or integrity, but availability is crucial for operational continuity. Organizations with remote or poorly secured router management interfaces are particularly vulnerable. Additionally, repeated exploitation attempts could degrade network performance or cause cascading failures in dependent systems. The absence of known exploits currently reduces immediate risk, but the potential for future weaponization exists. The impact is magnified in environments where Totolink A7000R routers are widely deployed without proper segmentation or access controls.

To mitigate this vulnerability, European organizations should immediately restrict access to the router’s management interface by disabling remote administration or limiting it to trusted IP addresses. Network segmentation should be employed to isolate management interfaces from general user networks. Monitoring network traffic for unusual or malformed requests targeting the wifiOff parameter or related endpoints can help detect exploitation attempts. Organizations should implement strict input validation and firewall rules to block suspicious packets. Until an official patch is released, consider replacing affected devices with alternative hardware or firmware versions not impacted by this vulnerability. Regularly check for firmware updates from Totolink and apply them promptly once available. Additionally, educating network administrators about this vulnerability and enforcing strong network security policies will reduce the attack surface. Incident response plans should include steps for rapid recovery from DoS conditions caused by this flaw.