CVE-2025-3989 is a critical buffer overflow vulnerability identified in the TOTOLINK N150RT wireless router, specifically in firmware version 3.4.0-B20190525. The vulnerability resides in an unspecified functionality related to the /boafrm/formStaticDHCP endpoint, where manipulation of the 'Hostname' argument can trigger a buffer overflow condition. This flaw allows an attacker to remotely send crafted input to the device without requiring authentication or user interaction, exploiting the vulnerability over the network. The buffer overflow can lead to arbitrary code execution, potentially allowing the attacker to take full control of the affected router. Given the CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N) and a score of 8.7, the vulnerability is highly exploitable with low attack complexity and no user interaction needed, but it requires low privileges (likely a network-level access or limited authentication). The impact covers confidentiality, integrity, and availability, as an attacker could execute arbitrary commands, disrupt network services, or intercept and manipulate network traffic. Although no public exploits are currently observed in the wild, the disclosure of a proof-of-concept exploit increases the risk of exploitation. The TOTOLINK N150RT is a consumer-grade router commonly used in small office and home environments, which may be deployed in various European organizations, especially small businesses and remote offices. The vulnerability's exploitation could lead to network compromise, lateral movement, and data exfiltration within affected networks.

For European organizations, exploitation of this vulnerability could result in significant network security breaches. Compromised routers can serve as entry points for attackers to infiltrate internal networks, bypass perimeter defenses, and conduct further attacks such as man-in-the-middle, data interception, or deployment of malware. Small and medium enterprises (SMEs) using TOTOLINK N150RT devices may face disruption of internet connectivity, loss of sensitive data, and potential regulatory non-compliance under GDPR if personal data is exposed. The integrity of network communications could be undermined, affecting business operations and trust. Additionally, the availability of network services could be impacted, leading to downtime and operational losses. Given the remote exploitability without user interaction, attackers can automate attacks at scale, increasing the threat to organizations with widespread deployment of this device. The lack of a patch at the time of disclosure further elevates risk, necessitating immediate mitigation measures.

1. Immediate network segmentation: Isolate TOTOLINK N150RT devices from critical network segments to limit potential lateral movement if compromised. 2. Disable or restrict access to the /boafrm/formStaticDHCP endpoint if possible via device configuration or firewall rules to prevent exploitation attempts. 3. Monitor network traffic for unusual activity targeting the affected endpoint or unusual DHCP-related requests. 4. Replace or upgrade affected devices where possible, prioritizing models with vendor patches or newer firmware versions. 5. If firmware updates become available, apply them promptly after testing in a controlled environment. 6. Implement strict access controls on router management interfaces, including changing default credentials and limiting management access to trusted IPs. 7. Employ intrusion detection/prevention systems (IDS/IPS) with signatures for this vulnerability to detect and block exploit attempts. 8. Educate IT staff to recognize signs of router compromise and establish incident response procedures specific to network infrastructure devices. 9. For organizations with remote or home offices using these routers, provide guidance and support to end-users to secure or replace vulnerable devices.