CVE-2026-51626 in TOTOLINK
Summary
by MITRE • 08/28/2026
Incorrect access control in the getWiFiWpsCfg function of TOTOLINK T6 4.1.5cu.748_B20211015 allows unauthenticated attackers to obtain WPS configuration, including the current PIN, 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 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 getWiFiWpsCfg function, which is responsible for retrieving Wireless Protected Setup configuration details. This component fails to enforce proper authentication or authorization checks before processing requests that expose sensitive network parameters. As a result, any unauthenticated actor capable of reaching the administrative CGI endpoint can interact with this function without providing valid credentials. The attack vector involves sending a specifically crafted POST request to the /cgi-bin/cstecgi.cgi script, which serves as the gateway for various configuration and status queries on the router's web server.
The technical nature of this flaw is classified under CWE-284, Improper Access Control, where an actor bypasses established security boundaries due to insufficient validation of user privileges. In many embedded devices, certain administrative functions are inadvertently exposed or lack proper session verification logic. When a POST request containing the appropriate parameters for retrieving WPS configuration is submitted to the CGI endpoint, the server processes it and returns the requested data because the underlying code does not verify if the requester has an active authenticated session or sufficient role permissions. This oversight allows remote attackers who are on the same local network segment, or potentially over the internet if port forwarding rules exist for the management interface, to extract sensitive configuration details without prior authentication.
The operational impact of this vulnerability is significant due to the nature of the data exposed: the WPS PIN and related configuration settings. The Wi-Fi Protected Setup (WPS) protocol was designed to simplify network connection but has historically been plagued by security weaknesses, most notably its susceptibility to brute-force attacks against the eight-digit PIN. By obtaining the current WPS PIN through this unauthenticated access flaw, an attacker can initiate a rapid offline or online brute-force attack to recover the actual Wi-Fi passphrase. Once the wireless password is derived from the compromised PIN, the attacker gains full unauthorized access to the local network. This compromise enables further lateral movement, interception of unencrypted traffic, manipulation of DNS settings for phishing attacks, and potential exploitation of other devices connected to the same LAN segment that may have their own vulnerabilities or weak security postures.
From a threat intelligence perspective, this vulnerability aligns with MITRE ATT&CK techniques related to Initial Access and Credential Access. Specifically, it facilitates unauthorized access (T1078) by bypassing authentication mechanisms and allows for credential harvesting through the exposure of WPS PINs which can be converted into network passwords. The ability to retrieve configuration data without authorization also supports reconnaissance activities where attackers map out network topology and security configurations before launching more intrusive attacks.
Mitigation strategies must address both immediate remediation and long-term architectural improvements. The primary solution is for TOTOLINK to release a firmware update that patches the getWiFiWpsCfg function by implementing strict access control checks, ensuring that only authenticated users with administrative privileges can invoke this endpoint. Until such an update is available, network administrators should disable WPS functionality entirely if it is not strictly required, as disabling WPS removes the value of the exposed PIN for attackers. Additionally, changing the default management interface port and restricting access to trusted IP addresses via firewall rules on upstream routers or firewalls can reduce the attack surface. Enabling strong, unique administrative passwords and ensuring that remote administration features are disabled unless absolutely necessary further hardens the device against exploitation attempts from external networks. Regular monitoring of network traffic for unusual POST requests to CGI endpoints may also aid in early detection of such probing activities.