CVE-2026-75784 in TEW-WLC100
Summary
by MITRE • 08/18/2026
A vulnerability was detected in TRENDnet TEW-WLC100 1v2.07b01. Affected by this issue is the function FUN_0040da4c of the file /usr/nginx/sbin/nginx of the component HTTP Header Handler. The manipulation of the argument Server results in stack-based buffer overflow. The attack may be launched remotely. The exploit is now public and may be used.
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Analysis
by VulDB Data Team • 08/18/2026
The identified vulnerability resides within the TRENDnet TEW-WLC100 wireless controller running firmware version 1v2.07b01, specifically affecting the HTTP Header Handler component implemented in the nginx web server binary located at /usr/nginx/sbin/nginx. The core technical flaw is a stack-based buffer overflow triggered by improper validation of input data associated with the Server argument within function FUN_0040da4c. This type of memory corruption occurs when the application copies user-supplied or network-received data into a fixed-size buffer on the call stack without adequately checking the length of the incoming payload, allowing an attacker to write beyond the allocated boundaries and overwrite adjacent memory locations including return addresses or function pointers.
From a technical perspective, this vulnerability aligns with Common Weakness Enumeration (CWE) ID 120, which classifies Buffer Copy without Checking Size of Input. The exploitation mechanism relies on crafting a specially crafted HTTP request where the Server header value exceeds the expected buffer size defined in the nginx configuration or source code logic for that specific function. By carefully calculating the offset and injecting shellcode or ROP gadgets into the overflowed stack space, an attacker can hijack the control flow of the application. Since this component handles web server headers, it is directly exposed to network traffic, making the vulnerability remotely exploitable without requiring prior authentication on many default configurations where administrative interfaces are accessible over standard HTTP ports.
The operational impact of successfully exploiting this stack-based buffer overflow is severe and typically results in full remote code execution (RCE) with the privileges of the nginx process. In embedded devices like wireless controllers, these processes often run as root or have elevated system permissions to manage network configurations and hardware interfaces. Consequently, an attacker can gain complete control over the device, install persistent malware, pivot into the internal network, exfiltrate sensitive data such as Wi-Fi credentials or configuration files, and potentially use the compromised device as a botnet node for distributed denial-of-service attacks. The fact that public exploits are available significantly lowers the barrier to entry for attackers, increasing the likelihood of automated scanning and exploitation campaigns targeting this specific firmware version across the internet.
Mitigation strategies must prioritize immediate isolation and patching if an official update is provided by TRENDnet. In the absence of a vendor-supplied fix, administrators should implement network-level controls such as firewall rules to restrict access to the administrative interface from untrusted networks or block external HTTP traffic directed at port 80 or 443 on this device. Additionally, deploying intrusion detection systems with signatures capable of detecting buffer overflow attempts involving oversized headers can provide a layer of defense-in-depth. It is also critical to disable unnecessary services and features within the nginx configuration if they are not required for the specific use case of the wireless controller, thereby reducing the attack surface available to potential adversaries leveraging this vulnerability in accordance with ATT&CK techniques related to initial access via web applications and command execution through remote exploitation.