Overview
A critical vulnerability has been identified in the TOTOLINK T6 firmware up to version 4.1.5cu.748_B20211015. This vulnerability pertains to a buffer overflow in the HTTP POST Request Handler’s setDiagnosisCfg function of the file /cgi-bin/cstecgi.cgi. The severity of this issue is accentuated by the public disclosure of the exploit, increasing the likelihood of its misuse by threat actors. This vulnerability is critical as it opens up the possibility for remote attacks, potentially enabling system compromise or data leakage.
Vulnerability Summary
CVE ID: CVE-2025-7758
Severity: Critical, CVSS score 8.8
Attack Vector: Remote
Privileges Required: None
User Interaction: None
Impact: Potential for system compromise or data leakage
Affected Products
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Product | Affected Versions
TOTOLINK T6 | up to 4.1.5cu.748_B20211015
How the Exploit Works
The vulnerability is exploited by manipulating the ‘ip’ argument in a HTTP POST request to the ‘/cgi-bin/cstecgi.cgi’ file. This manipulation results in a buffer overflow condition. Buffer overflow is a type of software vulnerability that exists when an area of a program’s memory that is used to store data can be overwritten with other data. This can cause the program to crash or, in the case of this exploit, allow an attacker to execute arbitrary code or system commands.
Conceptual Example Code
Here is a conceptual representation of a HTTP POST request that might be used to exploit this vulnerability:
POST /cgi-bin/cstecgi.cgi HTTP/1.1
Host: target.example.com
Content-Type: application/x-www-form-urlencoded
setDiagnosisCfg=1&ip=192.168.0.1[overflowing characters]In this example, ‘overflowing characters’ would be a crafted sequence of characters that cause the buffer overflow, potentially allowing the attacker to execute arbitrary code or system commands.
Mitigation Guidance
Users of affected TOTOLINK T6 versions are advised to apply the vendor patch as soon as it becomes available. In the interim, measures such as deploying Web Application Firewalls (WAFs) or Intrusion Detection Systems (IDS) can be used as temporary mitigation against potential attacks exploiting this vulnerability. Regular monitoring of network traffic for unusual or suspicious activities can also aid in early detection of any attempt to exploit this vulnerability.