CVE-2026-1547 is a command injection vulnerability identified in the Totolink A7000R router firmware version 4.1cu.4154. The vulnerability resides in the setUnloadUserData function of the /cgi-bin/cstecgi.cgi CGI script, where the plugin_name argument is improperly sanitized, allowing an attacker to inject arbitrary OS commands. This flaw can be exploited remotely over the network without requiring authentication or user interaction, making it a critical vector for remote compromise. The vulnerability's CVSS 4.0 score is 5.3, reflecting a medium severity due to partial impacts on confidentiality, integrity, and availability, and the lack of required privileges or user interaction. Exploitation could enable attackers to execute commands with the privileges of the web server process, potentially leading to device control, network traffic interception, or disruption of service. Although no official patches or vendor advisories are currently available, public exploit code has been released, increasing the likelihood of active exploitation. The affected product, Totolink A7000R, is a consumer and small office router, commonly deployed in various regions including Europe. The vulnerability highlights the risks of insufficient input validation in embedded device web interfaces, a common attack surface in IoT and networking equipment.

For European organizations, exploitation of this vulnerability could lead to unauthorized control over affected routers, enabling attackers to intercept or manipulate network traffic, disrupt connectivity, or pivot into internal networks. This is particularly concerning for small and medium enterprises or branch offices relying on Totolink A7000R devices for network access. Confidentiality may be compromised through data interception; integrity could be affected by malicious configuration changes or injected commands; availability might be degraded by denial-of-service conditions triggered via command execution. The lack of authentication requirement increases the attack surface, allowing remote attackers to target exposed devices directly. Given the public availability of exploit code, the risk of widespread attacks is elevated. European organizations with limited network segmentation or outdated firmware are especially vulnerable. The impact extends beyond individual devices to potentially affect broader organizational network security and operational continuity.

1. Immediately restrict remote access to the router's management interface by disabling WAN-side administration or limiting access via firewall rules to trusted IP addresses. 2. Conduct a thorough inventory of deployed Totolink A7000R devices and verify firmware versions to identify vulnerable units. 3. Monitor network traffic for unusual patterns or command injection attempts targeting the /cgi-bin/cstecgi.cgi endpoint. 4. Implement network segmentation to isolate vulnerable devices from critical infrastructure and sensitive data. 5. Apply vendor firmware updates as soon as they become available; if no official patch exists, consider temporary device replacement or enhanced monitoring. 6. Use intrusion detection/prevention systems (IDS/IPS) with signatures for known exploit attempts targeting this vulnerability. 7. Educate IT staff on the risks of embedded device vulnerabilities and the importance of timely patch management. 8. Consider deploying network access control (NAC) solutions to enforce device compliance and limit exposure.