CVE-2025-63462 is a stack-based buffer overflow vulnerability identified in the Totolink A7000R router firmware version 9.1.0u.6115_B20201022. The vulnerability arises from improper bounds checking in the sub_421A04 function when processing the wifiOff parameter. An attacker can craft a specially malformed request that overflows the stack buffer, leading to a denial of service by crashing or rebooting the device. The flaw does not require authentication or user interaction, making it remotely exploitable over the network. The vulnerability is classified under CWE-121 (Stack-based Buffer Overflow) and has a CVSS v3.1 base score of 7.5, indicating high severity. The attack vector is network-based (AV:N), with low attack complexity (AC:L), no privileges required (PR:N), and no user interaction needed (UI:N). The impact is limited to availability (A:H) with no confidentiality or integrity loss. Currently, no public exploits or patches are available, increasing the urgency for defensive measures. The Totolink A7000R is commonly used in SOHO environments, and disruption could affect internet connectivity and network services. The vulnerability highlights the need for secure firmware development and timely patch management in network infrastructure devices.

For European organizations, exploitation of CVE-2025-63462 could result in denial of service of Totolink A7000R routers, causing network outages and loss of internet connectivity. This can disrupt business operations, especially for small and medium enterprises relying on these devices for critical communications and remote access. The lack of confidentiality and integrity impact limits data breach risks, but availability loss can affect productivity, VoIP services, and access to cloud resources. In sectors such as healthcare, finance, and public administration, even short-term network disruptions can have significant operational and reputational consequences. The vulnerability's remote exploitability without authentication increases the attack surface, particularly if routers are exposed to the internet or untrusted networks. Organizations with inadequate network segmentation or weak perimeter defenses are more vulnerable. The absence of patches means mitigation relies on network controls and monitoring until vendor updates are released.

1. Immediately restrict access to the Totolink A7000R router management interfaces by implementing firewall rules that block incoming traffic on management ports from untrusted networks, especially the internet. 2. Segment the network to isolate SOHO routers from critical infrastructure and sensitive systems, reducing the blast radius of potential DoS attacks. 3. Monitor network traffic for unusual or malformed requests targeting the wifiOff parameter or related router endpoints, using IDS/IPS solutions with custom signatures if possible. 4. Disable remote management features on the router if not required, minimizing exposure. 5. Maintain up-to-date inventory of Totolink devices and their firmware versions to prioritize patching once vendor updates become available. 6. Engage with Totolink support channels to obtain information on forthcoming patches or workarounds. 7. Educate users and administrators about the risks of exposing router interfaces and the importance of secure configuration. 8. Consider deploying alternative routers with stronger security postures in environments where Totolink devices are critical and patching is delayed.