CVE-2026-77988 in TEW-823DRU
Summary
by MITRE • 08/22/2026
A weakness has been identified in TRENDnet TEW-823DRU 1.1.02b01. This vulnerability affects the function nvram_get of the component CLI Configuration Tool. This manipulation causes command injection. The attack is possible to be carried out remotely. The exploit has been made available to the public and could be used for attacks.
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Analysis
by VulDB Data Team • 08/22/2026
The TRENDnet TEW-823DRU router, specifically running firmware version 1.1.02b01, contains a critical security flaw within its Command Line Interface configuration tool that allows for remote command injection. This vulnerability is rooted in the improper handling of input data by the nvram_get function, which is responsible for retrieving non-volatile random-access memory values used to store persistent device settings. When this component processes user-supplied input without adequate sanitization or validation, it fails to distinguish between legitimate configuration parameters and malicious shell commands. This lack of rigorous input filtering creates a direct pathway for attackers to inject arbitrary operating system commands into the router's underlying Linux environment, effectively bypassing intended security controls and gaining unauthorized access to the device's administrative functions.
From a technical perspective, this flaw is classified under CWE-78, which denotes Improper Neutralization of Special Elements used in an OS Command, commonly known as OS Command Injection. The vulnerability arises because the nvram_get function likely passes unsanitized variables directly into system calls or shell interpreters such as sh or bash. An attacker can exploit this by crafting specific HTTP requests that target configuration endpoints where these values are processed. By embedding special characters like semicolons, pipes, or ampersands within the input fields, an adversary can terminate the intended command and append their own malicious commands for execution with the privileges of the compromised service, which often runs as root on embedded Linux devices.
The operational impact of this vulnerability is severe due to its remote nature and the availability of public exploits. Since the attack vector is network-based, a threat actor does not need physical access or prior authentication in many configurations where default credentials are still active or weak passwords are used. The existence of publicly available exploit code significantly lowers the barrier to entry for attackers, enabling widespread automated attacks against vulnerable devices on the internet. Successful exploitation can lead to complete compromise of the router, allowing the attacker to intercept network traffic, redirect users to malicious sites, use the device as part of a botnet for distributed denial-of-service attacks, or pivot into internal networks behind the firewall. This represents a significant risk to both home and small business environments relying on this hardware for secure connectivity.
Mitigation strategies must focus on immediate remediation through firmware updates if available from TRENDnet, ensuring that any patches addressing input validation in the CLI tool are applied. In cases where an update is not immediately accessible or applicable, network-level controls should be implemented to restrict access to the router's management interface. This includes disabling remote administration features and configuring firewalls to allow administrative traffic only from trusted internal IP addresses. Additionally, users should enforce strong, unique passwords for all accounts associated with the device and disable unused services such as Telnet or UPnP if they are not required. Regular monitoring of network logs for anomalous outbound connections can also help in detecting potential compromise early, although prevention through patching remains the most effective defense against this class of vulnerability aligned with ATT&CK techniques related to command and script interpretation.