CVE-2026-51637 in TOTOLINK
Summary
by MITRE • 08/28/2026
Incorrect access control in the getMeshPortalTable function of TOTOLINK T6 4.1.5cu.748_B20211015 allows unauthenticated attackers to obtain mesh portal table 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 the TOTOLINK T6 router, specifically within firmware version 4.1.5cu.748_B20211015, represents a critical failure in access control mechanisms governing administrative functions. The flaw resides in the getMeshPortalTable function, which is exposed through the web management interface at the endpoint /cgi-bin/cstecgi.cgi. This component is designed to retrieve and display configuration details regarding mesh networking portals, information that should be strictly restricted to authenticated administrators with appropriate privileges. However, due to insufficient validation of user session states or authentication tokens prior to executing this function, the system fails to enforce proper authorization checks. Consequently, any entity capable of reaching the router's web interface over a network connection can interact with this endpoint without providing valid credentials.
From a technical perspective, the exploitation vector involves sending a specifically crafted POST request to the identified CGI script. Unlike GET requests which might be logged or limited by browser security policies in some contexts, POST requests allow for more complex data transmission and are often less scrutinized if input validation is weak. The attacker constructs an HTTP POST message targeting /cgi-bin/cstecgi.cgi with parameters that trigger the getMeshPortalTable function. Because the server-side logic does not verify whether the requester has successfully authenticated or possesses administrative rights, it processes the request and returns sensitive configuration data. This behavior indicates a fundamental oversight in implementing role-based access control (RBAC) principles within the router's web application layer.
The operational impact of this vulnerability is significant for network security posture. Mesh portal table information typically contains details about connected nodes, their IP addresses, signal strengths, routing paths, and potentially shared keys or authentication parameters used to maintain mesh connectivity. An unauthenticated attacker gaining access to this data can perform reconnaissance activities that facilitate further attacks. For instance, knowledge of the mesh topology allows an adversary to identify vulnerable endpoints within the network segment. They may also use this information to craft targeted man-in-the-middle attacks against specific nodes in the mesh or to disrupt network stability by exploiting known weaknesses in the routing logic revealed by the table structure. In severe cases, if the exposed data includes cryptographic material related to node authentication, it could lead to full compromise of the mesh network integrity.
This vulnerability aligns with CWE-284, which describes Improper Access Control, as well as CWE-862, Missing Authorization Check. The exploitation technique corresponds to ATT&CK tactic TA0001 (Initial Access) and specifically relates to techniques involving web application attacks where the attacker leverages misconfigured permissions to gain unauthorized access to resources. It also touches upon information disclosure aspects found in data exfiltration tactics if the retrieved mesh table is sent out of band, though primarily it serves as a reconnaissance enabler under TA0043 (Reconnaissance).
Mitigation strategies must focus on immediate patching and network-level controls until an official firmware update is available. Users should upgrade to the latest stable firmware version released by TOTOLINK that addresses this specific access control flaw in the getMeshPortalTable function. If upgrading is not immediately feasible, administrators can implement temporary mitigations such as restricting access to the web management interface via firewall rules or ACLs (Access Control Lists) so that only trusted IP addresses can reach /cgi-bin/cstecgi.cgi. Additionally, disabling remote administration features if they are not required reduces the attack surface by preventing external network entities from even attempting to interact with the vulnerable endpoint. Regular monitoring of administrative logs for unusual POST requests to CGI scripts can also aid in early detection of exploitation attempts.