CVE-2025-63461 is a stack overflow vulnerability identified in the Totolink A7000R router firmware version 9.1.0u.6115_B20201022. The flaw exists in the handling of the ssid5g parameter within the urldecode function. When an attacker sends a specially crafted request containing a malformed ssid5g parameter, it triggers a stack overflow condition. This overflow can cause the router's process to crash or become unstable, resulting in a Denial of Service (DoS) condition that disrupts network connectivity for users relying on the device. The vulnerability does not require authentication, meaning an attacker with network access to the router's management interface or exposed services can exploit it. No public exploits or proof-of-concept code have been reported to date, and no official patches or firmware updates have been linked to this vulnerability. The absence of a CVSS score limits standardized severity assessment, but the nature of the vulnerability suggests a moderate risk primarily affecting availability. The vulnerability is specific to the Totolink A7000R model and the specified firmware version, limiting its scope to networks deploying this hardware. Attackers could leverage this flaw to disrupt business operations or home network connectivity by causing router crashes, potentially impacting productivity and access to network resources.

For European organizations, the primary impact of CVE-2025-63461 is the potential disruption of network availability due to router crashes. Organizations relying on Totolink A7000R routers, particularly in small office/home office (SOHO) environments or branch offices, may experience intermittent or prolonged loss of internet connectivity and internal network access. This can affect business continuity, remote work capabilities, and access to cloud services. While the vulnerability does not directly compromise data confidentiality or integrity, the denial of service can indirectly impact operational efficiency and user productivity. Critical infrastructure or organizations with limited IT support may face challenges in quickly restoring network functionality. Additionally, if attackers combine this DoS with other attack vectors, it could facilitate further exploitation or lateral movement within a network. The lack of known exploits reduces immediate risk, but the vulnerability should be addressed proactively to prevent future exploitation.

1. Restrict access to the router's management interface by limiting it to trusted internal networks and disabling remote management where possible. 2. Monitor Totolink's official channels for firmware updates addressing this vulnerability and apply patches promptly once available. 3. Implement network segmentation to isolate critical systems from devices using vulnerable routers. 4. Employ network intrusion detection systems (NIDS) to monitor for unusual or malformed requests targeting router management interfaces. 5. Regularly audit and inventory network hardware to identify devices running the affected firmware version. 6. Educate users and IT staff about the risks of exposing router management interfaces to untrusted networks. 7. Consider deploying alternative routers with better security track records in environments where Totolink devices are widely used. 8. Maintain backups of router configurations to facilitate rapid recovery after a crash or reboot caused by exploitation.