CVE-2026-76589 in TEW-755AP
Summary
by MITRE • 08/20/2026
A vulnerability was found in TRENDnet TEW-755AP up to 20260702. Affected is the function FUN_401000 of the file /sbin/mycli. The manipulation of the argument ssid results in stack-based buffer overflow. The attack may be launched remotely. The exploit has been made public and could be used.
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Analysis
by VulDB Data Team • 08/20/2026
The vulnerability identified in TRENDnet TEW-755AP firmware versions up to build 20260702 represents a critical security flaw within the device's command-line interface utility, specifically located in the function FUN_401000 of the /sbin/mycli binary. This issue is classified as a stack-based buffer overflow, which occurs when the application writes more data to a fixed-length block of memory on the call stack than it can hold. In this specific instance, the flaw is triggered by the manipulation of the ssid argument, likely during the processing of wireless network configuration parameters or authentication requests. The lack of proper bounds checking allows an attacker to overwrite adjacent memory locations on the stack, potentially overwriting return addresses and control flow data with malicious payloads.
From a technical perspective, this vulnerability falls under CWE-121: Stack-based Buffer Overflow, which is one of the most common causes of remote code execution vulnerabilities in embedded systems. The /sbin/mycli binary typically handles administrative commands or configuration updates sent to the device's operating system. When an attacker provides a specially crafted ssid string that exceeds the allocated buffer size, they gain the ability to inject and execute arbitrary machine code within the context of the process running mycli. Given that such utilities often run with elevated privileges on embedded devices like wireless access points, successful exploitation can lead to complete compromise of the device's integrity and confidentiality.
The operational impact of this vulnerability is severe due to its remote exploitability. Since the attack vector is network-based, an adversary does not need physical access or local authentication to trigger the overflow. They only require connectivity to the affected service port that processes these ssid arguments, which could be exposed via management interfaces or potentially through specific wireless protocol interactions depending on how the firmware handles incoming configuration data. The fact that a public exploit exists significantly lowers the barrier for entry, enabling automated attacks and widespread exploitation by threat actors seeking to hijack IoT devices for botnet recruitment, lateral movement within local networks, or as pivot points for further intrusions into connected systems.
This vulnerability aligns with several tactics in the MITRE ATT&CK framework, particularly T1059 Command and Scripting Interpreter if the overflow leads to shell execution, and potentially T1190 Exploit Public-Facing Application given its remote nature. The presence of a public exploit indicates that this is not merely theoretical but an active threat vector currently being leveraged in the wild or by security researchers demonstrating proof-of-concept attacks. Organizations relying on TRENDnet TEW-755AP devices are at immediate risk if these units remain unpatched and connected to networks where unauthorized access is possible, whether through direct internet exposure or compromised internal segments.
Mitigation strategies must prioritize immediate remediation of the firmware vulnerability by updating to a version released after July 2026 that addresses this buffer overflow condition in /sbin/mycli. If an official patch is unavailable or delayed, network segmentation should be implemented to restrict access to the management interfaces and configuration ports of these devices from untrusted networks. Additionally, deploying intrusion detection systems with signatures capable of detecting stack-based overflow patterns associated with ssid parameter manipulation can provide a layer of defense against exploitation attempts. Long-term security posture improvements include replacing legacy embedded firmware that lacks robust memory safety mechanisms and conducting regular vulnerability assessments on all IoT assets to ensure timely patching of known critical flaws.