CVE-2025-63154 identifies a stack overflow vulnerability in the TOTOLink A7000R router firmware version V9.1.0u.6115_B20201022. The vulnerability resides specifically in the addEffect parameter within the urldecode function. When a specially crafted POST request is sent to the device, it triggers a stack overflow condition, which causes the device to crash or reboot, resulting in a Denial of Service (DoS). This vulnerability is classified under CWE-121 (Stack-based Buffer Overflow), indicating that improper handling of input data leads to memory corruption on the stack. The vulnerability is remotely exploitable without any authentication or user interaction, increasing its risk profile. The CVSS v3.1 base score is 7.5, reflecting high severity due to network attack vector, low attack complexity, no privileges required, no user interaction, and impact limited to availability (no confidentiality or integrity impact). No patches or firmware updates are currently linked, and no active exploits have been reported in the wild. The vulnerability could be leveraged by attackers to disrupt network connectivity or cause outages in environments where these routers are deployed, impacting business continuity and operational stability.

For European organizations, the primary impact of CVE-2025-63154 is the potential for network disruption caused by Denial of Service attacks targeting TOTOLink A7000R routers. This can lead to loss of internet connectivity, interruption of critical services, and operational downtime. Organizations relying on these routers for internet access, VPN termination, or internal network routing could experience degraded service availability. In sectors such as finance, healthcare, manufacturing, and government, such disruptions could have cascading effects on productivity and service delivery. Additionally, the lack of confidentiality or integrity impact means data breaches are unlikely, but the availability impact alone can be costly. The vulnerability's remote exploitability without authentication increases the attack surface, especially if devices are exposed to untrusted networks or the internet. European organizations with limited network segmentation or inadequate perimeter defenses may be more vulnerable to exploitation attempts.

1. Monitor TOTOLink's official channels for firmware updates addressing CVE-2025-63154 and apply patches promptly once released. 2. Restrict access to router management interfaces by implementing network segmentation and firewall rules that limit administrative access to trusted internal IP addresses only. 3. Disable remote management features if not required, or enforce strong authentication and encrypted management protocols. 4. Deploy intrusion detection/prevention systems (IDS/IPS) capable of detecting anomalous POST requests or patterns indicative of exploitation attempts targeting the addEffect parameter. 5. Conduct regular network traffic analysis to identify unusual POST requests to the router that could signify exploitation attempts. 6. For critical environments, consider replacing vulnerable TOTOLink A7000R devices with alternative routers that have a stronger security posture and active vendor support. 7. Educate network administrators on this vulnerability to ensure rapid response and incident handling if exploitation is suspected.