CVE-2026-51625 in TOTOLINK
Summary
by MITRE • 08/28/2026
Incorrect access control in the getWiFiEasyCfg function of TOTOLINK T6 4.1.5cu.748_B20211015 allows unauthenticated attackers to obtain sensitive information such as 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 getWiFiEasyCfg function, which is exposed through the Common Gateway Interface (CGI) endpoint located at /cgi-bin/cstecgi.cgi. This architectural oversight allows unauthenticated actors to interact with sensitive configuration endpoints that should strictly require administrative privileges or valid session tokens for access. The absence of proper authentication checks means that any external user on the local network, and potentially over the internet if port forwarding is misconfigured, can issue requests to this endpoint without providing credentials.
From a technical perspective, the core defect is an insecure direct object reference combined with broken access control logic. When an attacker sends a crafted POST request to the specified CGI script, the server processes the command and returns detailed wireless configuration data. This includes Service Set Identifiers (SSIDs) which reveal network names and potentially organizational identifiers, as well as Wi-Fi keys or pre-shared keys that are essential for authenticating devices to the wireless network. The retrieval of these credentials via an unauthenticated vector indicates a fundamental misconfiguration in how the web server validates user intent versus actual permission levels before executing sensitive queries.
The operational impact of this vulnerability is severe and multifaceted. First, it leads directly to the disclosure of confidential information, categorized under CWE-200: Information Exposure. Attackers can harvest SSIDs to perform targeted social engineering attacks or wardriving activities based on known network topologies. More critically, the exposure of Wi-Fi keys allows attackers to gain full unauthorized access to the local area network. Once inside the LAN, an attacker can intercept unencrypted traffic, launch man-in-the-middle attacks against other connected devices, pivot into internal corporate networks if present, or compromise Internet of Things (IoT) devices that often lack robust security controls. This aligns with ATT&CK technique T1078: Valid Accounts, as the attacker effectively uses valid but stolen credentials to maintain persistent access and move laterally within the network environment.
Mitigation strategies must address both immediate remediation and long-term architectural improvements. The primary solution is for users to update their router firmware to a patched version released by TOTOLINK that corrects the authentication logic in the getWiFiEasyCfg function. Until an official patch is available, administrators should restrict access to the management interface by disabling remote administration features if they are not required. Additionally, implementing network segmentation can limit the blast radius of such a compromise; placing guest devices on a separate VLAN isolates them from critical infrastructure and sensitive data stores. Regular auditing of exposed CGI endpoints using vulnerability scanners that specifically test for broken access control flaws is also recommended to identify similar misconfigurations across other managed services within the enterprise environment.