CVE-2025-6916 in TOTOLINK
Summary
by MITRE • 06/30/2025
A vulnerability, which was classified as critical, was found in TOTOLINK T6 4.1.5cu.748_B20211015. This affects the function Form_Login of the file /formLoginAuth.htm. The manipulation of the argument authCode/goURL leads to missing authentication. The attack needs to be initiated within the local network. The exploit has been disclosed to the public and may be used.
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Analysis
by VulDB Data Team • 07/07/2025
This critical vulnerability exists in the TOTOLINK T6 router firmware version 4.1.5cu.748_B20211015 within the Form_Login function of the /formLoginAuth.htm file. The flaw specifically relates to improper handling of the authCode and goURL parameters, creating a significant authentication bypass weakness that allows unauthorized access to the device's administrative interface. The vulnerability's classification as critical indicates its potential for severe impact on network security and device integrity.
The technical implementation of this flaw involves the web application's insufficient validation of user-supplied input parameters during the authentication process. When the authCode and goURL arguments are manipulated, the system fails to properly verify the legitimacy of these inputs before granting access privileges. This represents a classic example of insufficient input validation that can be categorized under CWE-20, which addresses improper input validation in software applications. The vulnerability specifically manifests when these parameters are crafted to bypass the normal authentication flow, allowing attackers to gain administrative access without proper credentials.
The operational impact of this vulnerability is particularly concerning given that the attack requires only local network access, making it accessible to anyone within the same subnet. This local network requirement significantly increases the attack surface since most network environments contain numerous devices that could potentially be compromised. The fact that the exploit has been publicly disclosed means that threat actors can readily leverage this vulnerability without requiring advanced technical skills or expensive tools. This public availability transforms the vulnerability from a theoretical risk into an actual threat that can be exploited by malicious actors in the local network environment.
The security implications extend beyond simple unauthorized access, as administrative privileges on network devices can provide attackers with complete control over network traffic, configuration changes, and potential lateral movement within the network. This vulnerability could enable attackers to modify firewall rules, change DNS settings, install malicious software, or use the device as a pivot point for attacking other systems within the network. According to the MITRE ATT&CK framework, this represents a privilege escalation technique that could be categorized under T1068, which deals with local privilege escalation through exploitation of system vulnerabilities. The vulnerability also aligns with T1566, which covers social engineering tactics that may involve exploiting weak authentication mechanisms.
Organizations should immediately implement mitigations including firmware updates from TOTOLINK if available, network segmentation to isolate critical devices, and the implementation of network access control measures. The router should be configured with strong, unique passwords, and administrative access should be restricted to authorized personnel only. Additionally, network monitoring should be enhanced to detect unusual authentication patterns and unauthorized access attempts. Regular security assessments and vulnerability scanning should be conducted to identify similar weaknesses in other network devices and ensure comprehensive protection against similar attack vectors.