CVE-2026-51732 in TOTOLINK
Summary
by MITRE • 08/31/2026
Incorrect access control in the delWiFiScheduleCfg function of TOTOLINK T6 4.1.5cu.748_B20211015 allows unauthenticated attackers to remove Wi-Fi schedule entries 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 TOTOLINK T6 router, specifically within firmware version 4.1.5cu.748_B20211015, represents a critical failure in access control mechanisms governing network configuration parameters. The flaw resides in the delWiFiScheduleCfg function, which is responsible for deleting scheduled Wi-Fi settings that dictate when wireless networks are active or inactive. This component processes incoming HTTP POST requests directed at the /cgi-bin/cstecgi.cgi endpoint without adequately verifying whether the requesting entity possesses valid authentication credentials or sufficient privileges to perform such administrative actions. Consequently, any unauthenticated actor on the local network can interact with this interface and execute commands that modify critical security configurations.
From a technical perspective, the root cause is classified under CWE-269, which denotes Improper Privilege Context, as well as CWE-862, Missing Authorization. The web server component handling CGI requests fails to enforce session validation or token verification before passing parameters to the backend function responsible for modifying Wi-Fi schedules. This lack of enforcement allows an attacker to send a specifically crafted POST request containing the necessary arguments to delete existing schedule entries. Because this operation does not require prior authentication, it bypasses standard security controls designed to protect administrative interfaces from unauthorized modification.
The operational impact of this vulnerability is significant for both residential and small business environments relying on automated Wi-Fi scheduling features. By removing scheduled configurations, an attacker can effectively disable time-based access restrictions that may have been configured by the administrator. This could lead to unintended exposure of network resources during periods when they were intended to be offline or restricted. Furthermore, in some implementations, disrupting schedule integrity might interfere with quality of service policies or parental control features tied to specific times, thereby reducing the overall security posture and usability of the wireless network. An attacker leveraging this flaw can also potentially use it as a stepping stone for further enumeration if other related functions share similar authentication flaws.
This type of vulnerability aligns with MITRE ATT&CK technique T1548.003, Abuse Elevation Control Mechanism: Bypass User Interface Restrictions, where the attacker bypasses intended security controls by interacting directly with underlying APIs or endpoints rather than through the graphical user interface that typically enforces authentication prompts. It also relates to CWE-798, Use of Hard-coded Credentials, if the system relies on default session tokens that are easily predictable, though in this case, it is primarily a lack of any credential check for specific administrative functions.
To mitigate this risk, users should immediately update their TOTOLINK T6 firmware to the latest version released by the vendor, which likely includes patches enforcing proper authentication checks on all CGI endpoints handling configuration changes. If updating is not immediately feasible, administrators can implement network segmentation to isolate management interfaces from general user traffic or disable remote administration features if they are enabled over WAN connections. Additionally, deploying intrusion detection systems that monitor for abnormal POST requests targeting /cgi-bin/cstecgi.cgi with parameters related to schedule deletion can provide an additional layer of defense against exploitation attempts in real-time environments.