Executive Summary

CVE-2026-10206 is a critical buffer overflow vulnerability found in the D-Link DI-8400 device running firmware versions up to 16.07.26A1. The flaw exists in the /dbsrv.asp endpoint, specifically when handling the 'str' parameter in HTTP POST requests.

The vulnerability occurs because the device does not properly check the boundaries of the input when copying the 'str' parameter using the strcpy function. This allows an attacker to send an overly long payload that overflows the buffer on the stack.

Exploiting this vulnerability remotely can lead to denial of service (DoS) or arbitrary command execution on the affected device.

Useful 0 Not Useful 0

Impact Analysis

This vulnerability can have serious impacts including denial of service (DoS), where the device may crash or become unresponsive.

More critically, it can allow an attacker to execute arbitrary commands remotely on the affected D-Link DI-8400 device, potentially leading to full compromise of the device.

Such exploitation could allow attackers to disrupt network operations, intercept or manipulate data, or use the device as a foothold for further attacks within a network.

Useful 0 Not Useful 0

Detection Guidance

This vulnerability can be detected by monitoring for malicious HTTP POST requests targeting the /dbsrv.asp endpoint on D-Link DI-8400 devices. Specifically, look for POST requests containing an overly long payload in the 'str' parameter, which is used to trigger the buffer overflow.

A practical detection method is to capture network traffic and filter for POST requests to /dbsrv.asp with unusually large 'str' parameter values.

Example command using tcpdump to capture such traffic:

• tcpdump -i <interface> -A -s 0 'tcp port 80 and (((ip[2:2] - ((ip[0]&0xf)<<2)) - ((tcp[12]&0xf0)>>2)) != 0)' | grep -i 'POST /dbsrv.asp'

Alternatively, use tools like Wireshark to filter HTTP POST requests to /dbsrv.asp and inspect the 'str' parameter length for anomalies.

Useful 0 Not Useful 0

Mitigation Strategies

Immediate mitigation steps include restricting access to the vulnerable device's web interface to trusted networks only, such as internal management networks.

Implement network-level filtering to block or monitor HTTP POST requests to /dbsrv.asp, especially those containing large or suspicious payloads in the 'str' parameter.

If possible, disable or restrict access to the /dbsrv.asp endpoint until a firmware update or patch is applied.

Monitor for exploitation attempts by analyzing logs and network traffic for signs of buffer overflow attempts targeting this vulnerability.

Useful 0 Not Useful 0