External risk intelligence

TRENDnet TEW-WLC100 HTTP Header Handler Stack Buffer Overflow

CVE advisorySeverity: CRITICAL (CVSS 9.3)

CVE-2026-75784

The vulnerability affects a wireless controller's HTTP header handler within the nginx component. Such devices and their management interfaces are commonly exposed to the network to facilitate administration, making them public-facing or at least edge-reachable in standard deployment patterns.

Memory Corruption

Halo Surface Signal: 5 out of 5 — more likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A critical vulnerability has been identified in a TRENDnet wireless controller component that could allow remote attackers to trigger a stack-based buffer overflow. This issue is particularly concerning as exploit code is publicly available, increasing the risk of exploitation and potential impact on network management devices.

A bug in network equipment could be exploited remotely.
Public exploits increase the likelihood of an attack.
Confirm relevance and assess exposure to this risk.

Attack Path

How an attacker could exploit the issue

An attacker can reach the vulnerable component remotely by targeting the HTTP header handler in the device's nginx service. By manipulating the "Server" argument, an attacker can trigger a stack-based buffer overflow. This vulnerability can lead to a critical impact on the device.

No special access needed.
Manipulate "Server" argument.
Full system compromise.

Live Threat

Current exploitation, exposure, and threat context

A stack-based buffer overflow in the HTTP header handler of a TRENDnet wireless controller could allow remote attackers to impact the service's behavior. This could occur when specially crafted HTTP requests are sent to the device, potentially leading to an interruption or modification of the controller's functions.

System service availability.
Remote unauthenticated requests.
Service disruption or modification.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability affects TRENDnet wireless controllers, specifically impacting the HTTP header handler. Teams responsible for network infrastructure, device management, and application security should lead the response. The first practical step is to identify all instances of the affected device, determine their network exposure and business criticality, and locate the accountable system owner to coordinate remediation efforts.

Infrastructure and security teams own the issue.
Verify device exposure and business impact first.
Plan remediation based on identified risk.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

What is the TRENDnet TEW-WLC100?

The TRENDnet TEW-WLC100 is a wireless LAN controller. These devices are used in network environments to centrally manage multiple wireless access points, handling tasks like traffic routing, security configurations, and user connectivity across a managed Wi-Fi network.

What is a stack-based buffer overflow in CVE-2026-75784?

This is a memory corruption weakness, specifically CWE-121. It occurs when a program writes more data to a temporary memory storage area (the stack) than it is designed to hold. In this case, manipulating the 'Server' argument in the HTTP header handler forces this overflow, which can cause the device to crash or allow unauthorized control over its functions.

How is this vulnerability triggered?

An attacker triggers this by sending a specially crafted HTTP request to the device. The bug specifically resides in the nginx HTTP header handler. Requests that do not contain a manipulated 'Server' header argument or that are not directed at the device's management interface will not trigger this specific overflow.

Why does Halo Surface Signal consider this CVE high risk?

Halo Surface Signal flags this as very likely to be reachable because the affected nginx component manages the device's web interface. These management interfaces are frequently connected to the network to allow administrators access, meaning they are often exposed to the public internet or are easily accessible from the network edge.

What should I do if I run these wireless controllers?

Begin by auditing your network to identify all TEW-WLC100 units in your environment. Once identified, evaluate whether these devices need to be reachable from the network or internet. Coordinate with your network infrastructure team to restrict access where possible while you locate the system owners to prioritize and plan for necessary remediation steps.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.