Executive Summary

The CVE-2026-7079 vulnerability affects the Tenda F456 router, version 1.0.0.5. It is a stack-based buffer overflow found in the HTTP daemon (httpd), specifically within the fromAdvSetWan function.

This function processes user-supplied parameters "wanmode" and "PPPOEPassword." When the "wanmode" parameter is set to 2, the variable v16 is passed to a subroutine without any validation or length checking, which can cause a stack-based buffer overflow in the buffer "s."

Exploiting this vulnerability allows an attacker to perform a denial of service (DoS) or potentially execute arbitrary remote code on the device.

The attack can be initiated remotely by sending a specially crafted POST request to the /goform/AdvSetWan endpoint with "wanmode=2" and an excessively long "PPPOEPassword" parameter.

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Impact Analysis

This vulnerability can impact you by allowing an attacker to remotely cause a denial of service (DoS) on your Tenda F456 router, making it unavailable for legitimate use.

More severely, an attacker could exploit the buffer overflow to execute arbitrary code remotely, potentially gaining control over the device.

Such control could lead to unauthorized access, manipulation of network traffic, or use of the device as a foothold for further attacks within your network.

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Detection Guidance

This vulnerability can be detected by monitoring for suspicious POST requests to the /goform/AdvSetWan endpoint on the Tenda F456 router version 1.0.0.5. Specifically, look for requests where the parameter "wanmode" is set to 2 and the "PPPOEPassword" parameter contains an unusually long string, which may indicate an attempt to trigger the buffer overflow.

A practical detection method is to capture and analyze HTTP traffic targeting the router, focusing on POST requests to /goform/AdvSetWan with these parameters.

Example command using curl to test the vulnerability (for detection or proof of concept):

• curl -X POST http://[router_ip]/goform/AdvSetWan -d "wanmode=2&PPPOEPassword=$(python3 -c 'print("A"*500)')"

Network administrators can also use packet capture tools like tcpdump or Wireshark to filter and inspect HTTP POST requests to this endpoint.

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Mitigation Strategies

Immediate mitigation steps include restricting remote access to the router's management interface to trusted networks or IP addresses only, thereby reducing exposure to remote attacks.

If possible, disable remote management features temporarily until a patch or firmware update addressing this vulnerability is available.

Monitor network traffic for suspicious POST requests to /goform/AdvSetWan with unusual parameter values as described, and block or alert on such traffic.

Contact the vendor or check for firmware updates that fix this buffer overflow vulnerability and apply them as soon as they become available.

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Compliance Impact

The provided information does not specify how the CVE-2026-7079 vulnerability impacts compliance with common standards and regulations such as GDPR or HIPAA.

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