CVE-2025-28034 is a critical pre-authentication remote command execution (RCE) vulnerability affecting multiple TOTOLINK router models, specifically the A800R V4.1.2cu.5137_B20200730, A810R V4.1.2cu.5182_B20201026, A830R V4.1.2cu.5182_B20201102, A950RG V4.1.2cu.5161_B20200903, A3000RU V5.9c.5185_B20201128, and A3100R V4.1.2cu.5247_B20211129 firmware versions. The vulnerability resides in the NTPSyncWithHost function, which processes the hostTime parameter. Due to improper input validation, an attacker can inject arbitrary commands via this parameter, leading to remote code execution without requiring any authentication or user interaction. The underlying weakness corresponds to CWE-78 (Improper Neutralization of Special Elements used in an OS Command), indicating that the input is not properly sanitized before being passed to system-level commands. The CVSS v3.1 base score of 9.8 reflects the high severity, with an attack vector of network (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), and full impact on confidentiality, integrity, and availability (C:H/I:H/A:H). Although no public exploits have been reported yet, the ease of exploitation and critical impact make this vulnerability a significant threat to affected devices. TOTOLINK routers are commonly used in home and small office environments, and exploitation could allow attackers to fully compromise the device, pivot into internal networks, intercept or manipulate traffic, and disrupt network availability.

For European organizations, especially small and medium enterprises (SMEs) and home office users relying on TOTOLINK routers, this vulnerability poses a severe risk. Successful exploitation can lead to full device compromise, enabling attackers to execute arbitrary commands remotely without authentication. This can result in unauthorized access to internal networks, interception of sensitive communications, deployment of malware or ransomware, and disruption of business operations due to network outages. Given the critical nature of the vulnerability, attackers could also use compromised routers as footholds for lateral movement or as part of botnets for broader attacks. The impact is particularly concerning for organizations with limited IT security resources that may not promptly detect or mitigate such intrusions. Additionally, compromised routers could undermine compliance with European data protection regulations (e.g., GDPR) by exposing personal or sensitive data transmitted through the network.

1. Immediate firmware update: Organizations and users should verify their TOTOLINK router model and firmware version and apply any available firmware updates from TOTOLINK that address this vulnerability. Since no patch links are currently provided, monitoring official vendor channels for updates is critical. 2. Network segmentation: Isolate vulnerable routers from critical internal networks to limit potential lateral movement if compromised. 3. Disable or restrict NTP synchronization features if not required, or configure routers to synchronize only with trusted NTP servers. 4. Implement network-level protections such as firewall rules to restrict inbound access to router management interfaces and services, especially from untrusted external networks. 5. Monitor network traffic for unusual activity indicative of exploitation attempts, such as unexpected command execution or outbound connections from routers. 6. Consider replacing vulnerable devices with models from vendors with stronger security track records if timely patches are unavailable. 7. Educate users about the risks of using default or outdated router firmware and encourage regular security maintenance.