A critical stack-based buffer overflow in TRENDnet TEW-755AP allows remote attackers to compromise the device via a malformed PPPoE password argument.

This is a stack-based buffer overflow vulnerability within the ssi component of the device firmware. The flaw is triggered by sending a specially crafted argument to the wan.cgi script, which can be executed by an authenticated user with low privileges.

Successful exploitation of this vulnerability leads to full system compromise, potentially allowing an attacker to gain control over network traffic, intercept sensitive data, or render the device unusable. Given the critical CVSS score of 9.9, this vulnerability presents a severe risk to network integrity and confidentiality, warranting immediate remediation.

Immediate Action: Currently, no specific patch version is listed beyond the version identified as vulnerable. Please monitor the official TRENDnet support portal for firmware updates addressing this buffer overflow.

Proactive Monitoring: Review web access logs for unusual requests directed at the /cgi-bin/wan.cgi endpoint, specifically looking for abnormally long or suspicious character strings in arguments.

Compensating Controls: Deploy a Web Application Firewall (WAF) rule to inspect and block requests containing excessive payloads targeted at the aforementioned CGI script.

Public Exploit Available: Yes, a proof-of-concept Python script is available on GitHub.

This vulnerability represents a critical risk to the security of the TEW-755AP device. Given the existence of public proof-of-concept code, administrators should prioritize restricting access to the management interface to trusted internal networks and monitor for vendor-provided firmware updates to resolve this memory corruption flaw.