CVE-2026-51654 in TOTOLINK
Summary
by MITRE • 08/28/2026
Incorrect access control in the getScheduleCfg function of TOTOLINK T6 4.1.5cu.748_B20211015 allows unauthenticated attackers to obtain schedule or scheduled-reboot configuration information 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 TOTOLINK T6 router firmware version 4.1.5cu.748_B20211015 represents a critical failure in access control mechanisms within the device's web management interface. Specifically, the flaw resides in the getScheduleCfg function, which is responsible for retrieving configuration details related to scheduled tasks and automatic reboot settings. This component fails to enforce proper authentication checks before processing incoming requests, allowing unauthenticated actors to interact with sensitive administrative functions that should be restricted to authorized users only. The attack vector involves sending a specifically crafted POST request to the /cgi-bin/cstecgi.cgi endpoint, which serves as the primary interface for executing CGI scripts on the device. By exploiting this misconfiguration, an attacker can bypass security controls and extract internal configuration data without providing valid credentials.
From a technical perspective, this vulnerability is classified under CWE-284, Improper Access Control, specifically highlighting the failure to enforce authorization policies before granting access to resources or functions. The absence of session validation or token verification in the getScheduleCfg function means that any entity with network connectivity to the router's management interface can query these settings. This lack of enforcement is particularly dangerous because scheduled configurations often contain timing information for system updates, maintenance windows, and automatic reboots. Accessing this data allows an attacker to understand the operational rhythm of the target device, which can be leveraged to plan further attacks during periods when security patches might be applied or when administrative attention is likely to be diverted due to routine maintenance activities.
The operational impact of this information disclosure extends beyond simple configuration leakage. Knowledge of scheduled reboot times enables potential denial-of-service attacks by allowing an attacker to trigger reboots at inconvenient or critical moments, disrupting network availability for legitimate users. Furthermore, the extracted schedule data may reveal patterns in administrative behavior or system update cycles that could aid in developing more sophisticated exploits targeting other vulnerabilities present in the firmware version 4.1.5cu.748_B20211015. In a broader security context, this aligns with ATT&CK technique T1083, File and Directory Discovery, as the attacker is effectively enumerating system configuration files through web-based interfaces to gather intelligence about the target environment. This reconnaissance phase is often a precursor to more destructive actions such as privilege escalation or remote code execution if additional vulnerabilities are present in other CGI handlers.
Mitigation strategies for this vulnerability require immediate attention from both end-users and vendors. For users, it is imperative to update the router firmware to the latest version released by TOTOLINK, where access control checks have likely been strengthened to include proper authentication validation before executing sensitive functions like getScheduleCfg. If an updated firmware is not immediately available, administrators should consider restricting access to the management interface through network segmentation or firewall rules that limit exposure to trusted IP addresses only. Additionally, changing default administrative passwords and disabling remote management features can reduce the attack surface exposed to unauthenticated actors on public networks. Vendor response efforts must focus on implementing strict input validation and ensuring that all CGI endpoints enforce mandatory authentication checks consistent with industry best practices for secure web application development.