Command Injection in Tenda F451 Web Management Interface

Executive Summary

CVE-2026-11556 is a security vulnerability in the Tenda F451 router's web management interface, specifically in the formWriteFacMac function of the /goform/WriteFacMac endpoint.

The flaw is an OS command injection vulnerability caused by improper sanitization of the mac parameter. An attacker can send a specially crafted HTTP POST request that injects shell commands into this parameter.

This allows remote code execution (RCE) with root privileges on the device, potentially compromising the entire system.

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Impact Analysis

Exploitation of this vulnerability allows an attacker to execute arbitrary commands on the affected Tenda F451 router with root privileges.

This can lead to full system compromise, including unauthorized access, control over network traffic, data theft, or disruption of network services.

Since the exploit is publicly available, the risk of attacks is increased.

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Detection Guidance

This vulnerability can be detected by sending a crafted HTTP POST request to the /goform/WriteFacMac endpoint of the Tenda F451 router's web management interface. The request should include a malicious payload in the mac parameter to test for OS command injection.

For example, a command to test the vulnerability could be constructed to inject shell commands such as "ls" to verify if remote code execution is possible.

• Use curl or a similar tool to send a POST request with a payload like: curl -X POST http://<target-ip>/goform/WriteFacMac -d "mac=00:11:22:33:44:55;ls"
• Observe the response or behavior of the device to determine if the injected command executed, indicating the presence of the vulnerability.

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Mitigation Strategies

Immediate mitigation steps include restricting access to the web management interface of the Tenda F451 router to trusted networks or IP addresses only.

Avoid exposing the device's management interface to the internet or untrusted networks to reduce the risk of remote exploitation.

Monitor for unusual activity or unexpected commands being executed on the device, which may indicate exploitation attempts.

Apply any available firmware updates or patches from the vendor that address this vulnerability once they are released.

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Compliance Impact

The provided information does not specify how the CVE-2026-11556 vulnerability affects compliance with common standards and regulations such as GDPR or HIPAA.

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