CVE-2026-51726 in TOTOLINK
Summary
by MITRE • 08/31/2026
Incorrect access control in the delParentalRules function of TOTOLINK T6 4.1.5cu.748_B20211015 allows unauthenticated attackers to remove parental-control rules via sending a crafted POST request to /cgi-bin/cstecgi.cgi.
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Analysis
by VulDB Data Team • 08/31/2026
The vulnerability identified in the delParentalRules function of TOTOLINK T6 router firmware version 4.1.5cu.748_B20211015 represents a critical failure in access control mechanisms, specifically classified under CWE-284 Improper Access Control. This flaw allows unauthenticated attackers to bypass authentication requirements and execute administrative functions that should be restricted to authorized users. The core technical issue lies within the handling of HTTP POST requests directed at the /cgi-bin/cstecgi.cgi endpoint. In a properly secured system, any operation involving the modification or deletion of parental control rules would require valid session tokens, credentials, or other forms of authentication to verify the requester's identity and privileges. However, in this vulnerable implementation, the server fails to validate these security prerequisites before processing the request.
From an operational perspective, this lack of enforcement means that any external actor with network access to the router can send a specifically crafted POST request to trigger the deletion of parental control rules without providing valid login credentials. Parental controls are typically essential for restricting internet access based on time or content categories, often used by households and small businesses to enforce safety policies. The ability to remove these rules unauthenticated effectively neutralizes this security feature, potentially exposing users to inappropriate content or unauthorized network usage during restricted hours. This undermines the integrity of the device's configuration management capabilities and demonstrates a significant gap in the application layer security design.
This vulnerability aligns with ATT&CK technique T1078 Valid Accounts if an attacker were able to steal credentials first, but more accurately reflects aspects of privilege escalation or unauthorized access due to missing authentication checks. It also relates to CWE-352 Cross-Site Request Forgery (CSRF) principles in terms of state-changing actions being performed without proper verification of the request's origin and intent, although the primary flaw here is the absence of any authentication check rather than just token validation. The impact extends beyond mere configuration changes; it can lead to a broader compromise if parental controls were part of a larger security posture that included other restricted settings accessible through similar endpoints.
Mitigation strategies for this vulnerability involve immediate firmware updates provided by TOTOLINK, which should include patches enforcing strict authentication checks on all administrative CGI scripts. In the absence of an official patch, network administrators can implement temporary compensating controls such as restricting access to the router's management interface via firewall rules or VLAN segmentation to limit exposure to untrusted networks. Additionally, disabling remote administration features if not strictly necessary reduces the attack surface available to external attackers. Regular security audits and penetration testing focusing on authentication bypasses in embedded web interfaces are recommended to identify similar flaws before they can be exploited in production environments.