CVE-2025-4140: Critical Remote Buffer Overflow Vulnerability in Netgear EX6120 1.0.3.94

Overview

The cybersecurity landscape is fraught with ever-evolving threats and vulnerabilities. One such vulnerability is CVE-2025-4140, a critical buffer overflow issue found in Netgear EX6120 1.0.3.94. This vulnerability, affecting the function sub_30394, has the potential to compromise the entire system or lead to significant data leakage. The seriousness of this vulnerability lies in the fact that the attack can be initiated remotely, posing a severe threat to systems worldwide. Despite the early disclosure to the vendor, no response or remediation measures have been provided yet.

Vulnerability Summary

CVE ID: CVE-2025-4140
Severity: Critical (CVSS 8.8)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: System compromise, potential data leakage

Affected Products

Product | Affected Versions

Netgear EX6120 | 1.0.3.94

How the Exploit Works

The vulnerability stems from the function sub_30394 in Netgear EX6120 1.0.3.94, which fails to properly handle certain arguments related to the host. An attacker can exploit this issue by sending manipulated host arguments, causing the system to overflow its buffer. This overflow can then enable an attacker to execute arbitrary code on the system, possibly leading to full system control or data leakage. The risk is compounded by the fact that the attack can be launched remotely, allowing attackers to exploit this vulnerability from anywhere in the world.

Conceptual Example Code

Below is a conceptual example of how the vulnerability might be exploited. This is not a real exploit, but a representation of how an HTTP request might be manipulated to trigger the buffer overflow.

POST /sub_30394/function HTTP/1.1
Host: target.example.com
Content-Type: application/json
{
"host": "<malicious_payload>"
}

In this example, “ represents a specially crafted string designed to overflow the buffer, leading to potential execution of arbitrary code or system compromise. It is crucial to patch this vulnerability as soon as possible or employ WAF/IDS as a temporary mitigation measure until the vendor responds with a proper fix.