Executive Summary

CVE-2026-7122 is a command injection vulnerability found in the TOTOLINK A8000RU router, version 7.1cu.643_b20200521. It exists in the CGI Handler component, specifically in the function setUPnPCfg within the /cgi-bin/cstecgi.cgi file.

The vulnerability arises because a user-supplied parameter named "enable" is passed unchecked to a system command execution function. Attackers can craft malicious HTTP POST requests that inject arbitrary operating system commands via this parameter.

A proof of concept shows that an attacker can execute commands like listing directory contents, which confirms remote command execution without any authentication.

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Impact Analysis

This vulnerability allows remote attackers to execute arbitrary operating system commands on the affected router without authentication.

Such unauthorized command execution can lead to full compromise of the device, including unauthorized access to network traffic, modification or disruption of router functionality, and potential use of the device as a foothold for further attacks within the network.

Because the exploit is publicly disclosed, attackers can easily leverage this vulnerability to cause significant security breaches.

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Detection Guidance

This vulnerability can be detected by sending specially crafted HTTP POST requests to the /cgi-bin/cstecgi.cgi endpoint with the parameter "enable" containing OS commands. Successful exploitation results in execution of these commands on the device.

For example, a proof of concept uses the command `ls>./setUPnPCfg.txt` as the value of the "enable" parameter. If the device executes this command, it creates a file named setUPnPCfg.txt containing the directory listing, confirming the vulnerability.

To detect this on your network or system, you can use curl or similar tools to send the following POST request:

• curl -X POST http://[target-ip]/cgi-bin/cstecgi.cgi -d "enable=ls>./setUPnPCfg.txt"

After sending this request, check if the file setUPnPCfg.txt is created on the device or if the command output can be observed, indicating successful command injection.

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Compliance Impact

The CVE-2026-7122 vulnerability allows remote attackers to execute arbitrary operating system commands on the TOTOLINK A8000RU router without authentication. This poses a significant security risk by potentially compromising the confidentiality, integrity, and availability of data handled by the device.

Such a vulnerability could lead to unauthorized access or manipulation of sensitive data, which may result in non-compliance with common standards and regulations like GDPR and HIPAA that require protection of personal and health information.

However, the provided information does not explicitly describe the impact on compliance with these standards or any specific regulatory consequences.

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Mitigation Strategies

To mitigate the CVE-2026-7122 vulnerability in the TOTOLINK A8000RU router, immediate steps include restricting remote access to the affected device, especially to the /cgi-bin/cstecgi.cgi endpoint, to prevent unauthorized HTTP POST requests.

Additionally, disabling or limiting UPnP functionality if not required can reduce the attack surface.

Monitoring network traffic for suspicious POST requests targeting the vulnerable function and applying firewall rules to block such attempts is also recommended.

Finally, check for and apply any available firmware updates or patches from the vendor that address this command injection vulnerability.

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