CVE-2026-76591 in TEW-755AP
Summary
by MITRE • 08/20/2026
A security flaw has been discovered in TRENDnet TEW-755AP up to 20260702. This affects the function log_email_server of the file /cgi-bin/email.cgi of the component ssi. Performing a manipulation results in command injection. The attack is possible to be carried out remotely. The exploit has been released to the public and may be used for attacks.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 08/20/2026
The discovery of a critical remote code execution vulnerability within TRENDnet TEW-755AP firmware versions up to 20260702 represents a significant threat to network infrastructure security, particularly in environments relying on this specific access point model. The flaw resides specifically within the log_email_server function located in the /cgi-bin/email.cgi file, which is part of the server-side include (SSI) component responsible for handling email configuration and logging tasks. This architectural placement places the vulnerability at a critical intersection between user-facing web interfaces and backend system commands, creating an attack surface that is both accessible and potent. The presence of this flaw indicates a failure in input validation mechanisms during the processing of email server parameters, allowing malicious actors to inject arbitrary operating system commands directly into the underlying shell environment.
From a technical perspective, this vulnerability is classified as CWE-78 Improper Neutralization of Special Elements used in an OS Command commonly known as command injection. The root cause lies in the insufficient sanitization or escaping of user-supplied input before it is passed to system-level execution functions. When an attacker provides specially crafted data through the email configuration interface, the application fails to distinguish between legitimate configuration values and executable code fragments. This allows the injected payload to be interpreted by the operating system shell rather than being treated as static string data. The severity of this issue is compounded by its remote exploitability, meaning that authentication or physical proximity to the device is not required for an attacker to initiate the exploitation process over a network connection.
The operational impact of successfully exploiting this vulnerability is severe and comprehensive. An attacker can achieve arbitrary code execution with the privileges of the web server process running on the access point. In many embedded Linux-based devices like the TRENDnet TEW-755AP, these processes often run with elevated permissions or root-level access to facilitate configuration changes. Consequently, a successful exploit grants the adversary full control over the device. This can lead to the compromise of the entire local network segment connected through this access point, enabling activities such as traffic interception, man-in-the-middle attacks, and pivoting into more sensitive internal systems. Furthermore, because the vulnerability affects core logging functionality, it may also allow attackers to manipulate audit trails or disrupt security monitoring capabilities by corrupting log files or disabling alert mechanisms.
The fact that a public exploit has been released significantly elevates the risk profile of this vulnerability. Publicly available exploits lower the barrier to entry for malicious actors who lack advanced reverse engineering skills, leading to an increased likelihood of automated scanning and widespread exploitation across vulnerable deployments in the wild. This scenario aligns with MITRE ATT&CK techniques related to Command and Scripting Interpreter execution, specifically those involving remote services or web application attacks. The availability of ready-made tools means that defenders must prioritize remediation efforts immediately rather than waiting for vendor patches based on theoretical risk assessments alone.
Mitigation strategies should focus on immediate isolation and patch management where possible. Organizations utilizing the TRENDnet TEW-755AP should urgently apply any available firmware updates provided by the manufacturer, ensuring they verify the integrity of the update package to prevent supply chain compromises during the patching process. If a patched version is not yet available or cannot be applied immediately due to operational constraints, network segmentation becomes critical. The affected access points should be isolated from sensitive internal networks and placed in a demilitarized zone with strict firewall rules limiting inbound traffic to only necessary management protocols. Additionally, implementing deep packet inspection at the perimeter can help detect patterns associated with command injection payloads targeting CGI endpoints. Long-term remediation requires replacing vulnerable legacy hardware with modern devices that adhere to secure coding standards and undergo rigorous security testing before deployment.