CVE-2026-51646 in TOTOLINK
Summary
by MITRE • 08/28/2026
Incorrect access control in the getParentalRules function of TOTOLINK T6 4.1.5cu.748_B20211015 allows unauthenticated attackers to obtain parental-control rules 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 sensitive configuration data. The flaw resides in the getParentalRules function, which is exposed through the device's web management interface via the endpoint /cgi-bin/cstecgi.cgi. This architectural design allows any user interacting with the router to request parental control settings without requiring prior authentication or valid session tokens. In a properly secured system, such administrative functions should be gated behind strict identity verification processes to ensure that only authorized administrators can view or modify network policies. The absence of these checks means that the function operates in an open state relative to unauthenticated actors, violating fundamental principles of secure software design regarding privilege separation and data confidentiality.
From a technical perspective, this issue is classified as CWE-284, which denotes Improper Access Control. An attacker can exploit this weakness by crafting specific HTTP POST requests directed at the vulnerable CGI script. Because the server does not validate the requester's authentication status before processing the query for parental rules, it returns the requested data directly to the client. This behavior effectively bypasses the intended security boundary of the router’s administrative interface. The vulnerability is particularly concerning because parental control configurations often contain detailed information about network usage policies, potentially including whitelists or blacklists of websites and devices connected to the local area network. While this may not immediately expose raw passwords, it provides an attacker with significant intelligence regarding the network topology and security posture of the victim's environment.
The operational impact of this vulnerability extends beyond simple data leakage. By obtaining parental control rules, an adversary can map out which devices are present on the internal network based on how they are categorized or restricted by these policies. This information aids in reconnaissance efforts, allowing for more targeted subsequent attacks against specific endpoints that may have weaker security postures compared to others. Furthermore, understanding the existing restrictions helps attackers identify potential blind spots where malicious traffic might not be flagged by automated filtering systems already configured by the administrator. In the context of the MITRE ATT&CK framework, this activity aligns with T1087, Account Discovery, and potentially T1592, Gather Victim Host Information, as it facilitates the collection of environmental data that can be leveraged for lateral movement or further exploitation within a trusted network segment.
Mitigating this vulnerability requires immediate action from both device manufacturers and end-users. For vendors, the primary remediation involves implementing strict authentication checks within the getParentalRules function to ensure that only users with valid administrative credentials can access parental control data. This should include verifying session tokens or cookies associated with a logged-in administrator account before processing any requests related to sensitive configuration parameters. Additionally, input validation and rate limiting on the /cgi-bin/cstecgi.cgi endpoint can help mitigate automated exploitation attempts. For end-users, it is crucial to ensure that router firmware is updated to patched versions as soon as they become available from TOTOLINK. In environments where updates are not immediately possible, restricting physical access to the management interface and ensuring strong administrative passwords remain essential defensive measures to reduce the risk of unauthorized configuration changes or further exploitation leveraging this information disclosure.