CVE-2026-51708 in TOTOLINK
Summary
by MITRE • 08/31/2026
Incorrect access control in the setWiFiWpsCfg function of TOTOLINK T6 4.1.5cu.748_B20211015 allows unauthenticated attackers to change WPS availability 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 setWiFiWpsCfg 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 permits unauthenticated remote attackers to modify the Wi-Fi Protected Setup (WPS) configuration without providing valid credentials or session tokens. The attack vector involves sending a specially crafted HTTP POST request directly to the /cgi-bin/cstecgi.cgi endpoint, which serves as the primary interface for executing administrative commands on the device's embedded web server. By bypassing authentication checks that should be enforced before processing sensitive configuration changes, an attacker can manipulate core network security settings from any location where they have network connectivity to the target router.
The technical nature of this flaw lies in the insufficient validation performed by the setWiFiWpsCfg function upon receiving input parameters related to WPS status. In a properly secured implementation, such administrative functions would require verification of user privileges, typically through session cookies or authentication tokens generated after a successful login process. However, due to the absence of these checks, the firmware processes requests that alter the availability and state of WPS regardless of whether the requester is an authorized administrator or an external adversary. This lack of authorization enforcement allows for remote configuration manipulation without any form of user interaction on the device itself, making it a severe security risk in both home and small business environments where physical access to the router may not be available to potential attackers.
The operational impact of this vulnerability extends beyond simple misconfiguration; it significantly weakens the overall security posture of the network infrastructure managed by the TOTOLINK T6 router. WPS is designed as a convenience feature for connecting devices securely, but its implementation has historically been associated with weaknesses such as PIN brute-force attacks when enabled improperly or left in default states. By allowing an attacker to toggle WPS availability remotely, they can effectively enable this potentially vulnerable protocol on demand, thereby expanding the attack surface of the network. Furthermore, if combined with other vulnerabilities that exploit WPS PIN flaws, this access control issue could facilitate unauthorized network entry, leading to data interception, lateral movement within the local area network, or complete compromise of connected devices. The ability to disable WPS remotely might also disrupt legitimate user operations, serving as a vector for denial-of-service conditions against specific connectivity methods.
Mitigation strategies must address both immediate remediation and long-term security hardening. The primary solution is to apply firmware updates provided by TOTOLINK that patch the setWiFiWpsCfg function with proper authentication checks before processing configuration changes. Until such patches are available, administrators should manually disable WPS through any remaining secure administrative interface if accessible, or physically disconnect devices running vulnerable firmware from untrusted networks. Network segmentation can also help limit the blast radius of a successful exploitation by isolating IoT and guest traffic from critical internal resources. Additionally, implementing strict firewall rules to restrict access to /cgi-bin/cstecgi.cgi only from trusted IP addresses within the local network reduces exposure to remote attacks. From an industry standard perspective, this vulnerability aligns with ATT&CK technique T1546.008 Event Triggered Execution if used for persistence or T1078 Valid Accounts if it leads to privilege escalation scenarios in broader attack chains, highlighting the need for robust identity and access management practices even on embedded devices often overlooked by traditional security controls.