CVE-2026-51715 in TOTOLINK
Summary
by MITRE • 08/31/2026
Incorrect access control in the delMacFilterRules function of TOTOLINK T6 4.1.5cu.748_B20211015 allows unauthenticated attackers to remove MAC filter 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 delMacFilterRules function within TOTOLINK T6 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 execute administrative functions that should be restricted to authorized users with valid credentials. The core technical issue lies in the absence of proper authentication checks or session validation before processing requests intended to modify MAC filter rules on the device's network interface configuration. By sending a crafted POST request to the /cgi-bin/cstecgi.cgi endpoint, an attacker can bypass security controls and directly invoke this function without providing any form of user identification or proof of authorization.
From an operational perspective, the ability to remove MAC filter rules has significant implications for network segmentation and access control policies implemented at the router level. MAC filtering is often used as a basic layer of security to restrict which devices can connect to a wireless network based on their hardware addresses. If these filters are removed by an unauthorized party, it effectively opens up the network to any device capable of associating with the Wi-Fi signal, potentially leading to unauthorized access, data interception, or further exploitation of connected endpoints. This undermines the integrity and confidentiality of the local area network protected by the router.
The attack vector is remote and requires no prior authentication, which significantly lowers the barrier for entry for potential adversaries. The use of a POST request indicates that the vulnerability can be exploited through standard web application interaction methods or automated scripts, making it scalable and easy to exploit in targeted attacks. This aligns with ATT&CK technique T1078 Valid Accounts if an attacker were to compromise credentials first, but since this is unauthenticated, it falls more directly under exploitation of misconfigured access controls that allow privilege escalation through functional abuse rather than credential theft.
Mitigation strategies for this vulnerability primarily involve applying the latest firmware updates provided by TOTOLINK, which likely include patches to enforce proper authentication checks within the delMacFilterRules function and other administrative endpoints. Until such updates are applied, network administrators should consider implementing additional layers of security at the perimeter firewall level to restrict access to the router's management interface from untrusted networks. Additionally, disabling remote management features if not strictly necessary can reduce the attack surface exposed to external threats. Regular auditing of configuration changes and monitoring for unusual activity on the device can also help in detecting potential exploitation attempts early.