CVE-2026-51634 in TOTOLINK
Summary
by MITRE • 08/28/2026
Incorrect access control in the getWiFiBasicCfg function of TOTOLINK T6 4.1.5cu.748_B20211015 allows unauthenticated attackers to obtain core wireless settings, including SSIDs and Wi-Fi keys, 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 getWiFiBasicCfg function, which is designed to retrieve fundamental wireless configuration parameters such as Service Set Identifiers (SSIDs) and Wi-Fi encryption keys. Under normal operational conditions, this functionality should be restricted to authenticated administrators who have successfully logged into the router’s administrative panel. However, due to insufficient validation of user privileges before processing requests directed at this endpoint, an unauthenticated attacker can bypass authentication requirements entirely. This misconfiguration allows any external actor with network access to interact directly with the underlying CGI script without providing valid credentials or session tokens.
The technical mechanism exploited involves sending a specifically crafted HTTP POST request to the /cgi-bin/cstecgi.cgi endpoint. By targeting this specific gateway, attackers invoke the getWiFiBasicCfg function which returns sensitive wireless configuration data in plaintext format. The absence of proper authorization checks means that the server processes these requests as if they originated from an authorized administrator session. This lack of enforcement at the application layer effectively neutralizes any authentication controls implemented elsewhere in the system architecture. Consequently, the confidentiality of critical network security parameters is compromised, exposing SSIDs and pre-shared keys to potential interception by malicious actors operating within range or on the same local network segment.
The operational impact of this vulnerability extends beyond simple information disclosure. The exposure of Wi-Fi encryption keys allows attackers to decrypt wireless traffic captured via passive monitoring tools such as Wireshark or Aircrack-ng. With access to these credentials, an adversary can authenticate themselves to the wireless network, thereby gaining full Layer 2 connectivity. This unauthorized access facilitates further lateral movement within the local area network, potentially leading to the compromise of internal devices, data exfiltration, and disruption of services. Furthermore, knowledge of SSIDs aids in social engineering attacks or targeted brute-force attempts against other security protocols associated with those networks. The ability to retrieve these settings remotely without authentication significantly lowers the barrier for entry, making this vulnerability highly exploitable by automated scanning tools commonly found on platforms like Shodan or Censys.
From a classification perspective, this issue aligns directly with CWE-284, which describes Improper Access Control, specifically highlighting failures in authorization checks that allow unauthorized access to restricted resources. It also maps to the ATT&CK framework under T1078, Valid Accounts, as attackers leverage valid but unauthenticated credentials or lack thereof due to system misconfiguration to gain initial access and persistence within the network environment. The exploitation of this flaw enables reconnaissance activities categorized under T1592, Gather Victim Host Information, by revealing critical infrastructure details that aid in subsequent attack phases such as credential stuffing or man-in-the-middle attacks.
Mitigation strategies must prioritize immediate patching if a firmware update addressing this access control deficiency is available from the vendor. In cases where updates are not immediately accessible, network segmentation should be employed to restrict management interfaces from untrusted networks. Administrators can also implement firewall rules that block external HTTP POST requests targeting /cgi-bin/cstecgi.cgi unless explicitly required for legitimate administrative tasks. Additionally, enforcing strong password policies and disabling remote administration features reduces the attack surface available to potential exploiters. Regular audits of web application access controls are essential to ensure that sensitive configuration endpoints remain protected against unauthorized retrieval attempts.