Executive Summary

CVE-2026-5044 is a security vulnerability in the Belkin F9K1122 router firmware version 1.00.33. It is a stack-based buffer overflow found in the web interface's formSetSystemSettings function. The vulnerability occurs because the function copies a user-supplied parameter named "webpage" into a fixed-size buffer without checking its length, leading to an overflow.

An attacker can exploit this remotely by sending a specially crafted HTTP POST request with an excessively long "webpage" parameter to the /goform/formSetSystemSettings endpoint. This can cause the router to crash or allow the attacker to execute arbitrary code.

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Impact Analysis

This vulnerability can impact you by allowing a remote attacker to cause a denial of service on your Belkin F9K1122 router, making it unavailable.

More severely, the attacker may be able to execute arbitrary code remotely, potentially taking control of the device, which could lead to further network compromise or data interception.

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Detection Guidance

This vulnerability can be detected by monitoring for suspicious HTTP POST requests sent to the /goform/formSetSystemSettings endpoint of the Belkin F9K1122 router, specifically those containing an excessively long "webpage" parameter.

A detection method involves capturing network traffic and filtering for POST requests targeting /goform/formSetSystemSettings with unusually large payloads in the "webpage" parameter.

• Use a network packet capture tool like tcpdump or Wireshark to capture HTTP traffic.
• Example tcpdump command to capture relevant traffic: tcpdump -i <interface> -A 'tcp port 80 and (((ip[2:2] - ((ip[0]&0xf)<<2)) - ((tcp[12]&0xf0)>>2)) != 0)' | grep -i 'POST /goform/formSetSystemSettings'
• Inspect captured POST requests for the "webpage" parameter with abnormally large values, which may indicate an attempt to exploit the buffer overflow.

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Mitigation Strategies

Immediate mitigation steps include restricting access to the vulnerable endpoint and monitoring for exploit attempts.

• Block or restrict remote access to the /goform/formSetSystemSettings endpoint on the Belkin F9K1122 router, especially from untrusted networks.
• Implement network-level filtering or firewall rules to detect and block HTTP POST requests with unusually large "webpage" parameters targeting this endpoint.
• Monitor router logs and network traffic for signs of exploitation attempts.

Since the vendor has not responded with a patch, consider isolating the affected device from critical networks until a fix or update is available.

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Compliance Impact

The provided information does not specify how the CVE-2026-5044 vulnerability impacts compliance with common standards and regulations such as GDPR or HIPAA.

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