CVE-2026-51610 in TOTOLINK
Summary
by MITRE • 08/28/2026
Incorrect access control in the RebootSystem function of TOTOLINK T6 4.1.5cu.748_B20211015 allows unauthenticated attackers to arbitrarily force an immediate reboot via sending a crafted POST request to /cgi-bin/cstecgi.cgi.
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Analysis
by VulDB Data Team • 08/28/2026
The vulnerability identified in the TOTOLINK T6 router, specifically within firmware version 4.1.5cu.748_B20211015, represents a critical failure in access control mechanisms governing system-level administrative functions. The core technical flaw resides in the RebootSystem function, which is exposed through the device's web management interface at the endpoint /cgi-bin/cstecgi.cgi. This Common Gateway Interface script serves as an intermediary between user requests and backend router operations. In a properly secured implementation, any command that alters the state of the hardware or initiates a system restart must be protected by robust authentication checks to ensure that only authorized administrators can execute such actions. However, in this specific firmware version, the RebootSystem function lacks sufficient validation of the requester's credentials before proceeding with the reboot operation. This oversight allows unauthenticated attackers who have network access to the management interface to bypass security controls entirely.
From a technical perspective, an attacker exploits this flaw by crafting and sending a specifically formatted POST request directly to the /cgi-bin/cstecgi.cgi endpoint. Because the server does not verify whether the sender has valid administrative privileges or session tokens associated with a logged-in user, it accepts the command as legitimate. The payload typically involves specifying parameters that trigger the RebootSystem routine without requiring prior login authentication. This type of vulnerability is classified under CWE-284, which covers Improper Access Control, and more specifically aligns with CWE-306 regarding Missing Authentication for Critical Function. It demonstrates a fundamental breakdown in the principle of least privilege and secure default configurations, where sensitive administrative actions are not gated by identity verification mechanisms.
The operational impact of this vulnerability is severe due to its direct effect on system availability. By forcing an immediate reboot, an attacker can cause a Denial of Service condition for any devices relying on the router for network connectivity. This disruption affects all users connected to the local area network, potentially halting business operations or personal internet access depending on the deployment context. Furthermore, repeated forced reboots can lead to hardware wear and tear over time, although the primary concern remains the immediate loss of service. In environments where uptime is critical, such as in industrial control systems or enterprise networks, this vulnerability poses a significant risk to operational continuity. Additionally, if the reboot process involves clearing volatile memory without proper safeguards, it could potentially disrupt ongoing secure sessions or leave temporary security gaps during the restart phase.
This attack vector maps directly to techniques observed in real-world threat landscapes, particularly those documented in the MITRE ATT&CK framework under T1529 System Shutdown/Reboot. Adversaries often utilize such capabilities to evade detection by disrupting logging mechanisms, interrupting forensic analysis processes, or simply causing chaos within a targeted network segment. The ability to trigger this action remotely and without authentication makes it an attractive tool for both opportunistic attackers seeking disruption and more sophisticated actors aiming to degrade the reliability of critical infrastructure components.
Mitigation strategies must focus on immediate remediation through firmware updates provided by TOTOLINK, which likely address these access control deficiencies in newer releases. Administrators should ensure their devices are running the latest stable firmware version that patches this specific flaw. In cases where updating is not immediately feasible, network-level controls can provide temporary relief. Restricting access to the management interface /cgi-bin/cstecgi.cgi via firewall rules or VLAN segmentation ensures that only trusted IP addresses can reach these administrative endpoints. Additionally, disabling remote management features if they are not strictly necessary reduces the attack surface exposed to external networks. Implementing strong authentication policies and monitoring logs for unusual POST requests to critical CGI scripts can also aid in early detection of exploitation attempts.