CVE-2025-4342: Critical Buffer Overflow Vulnerability in D-Link DIR-600L

Overview

The cybersecurity industry has recently identified a critical vulnerability, CVE-2025-4342, affecting D-Link DIR-600L up to version 2.07B01. This vulnerability, classified as critical, has the potential to compromise systems and lead to data leakage, posing a significant security risk to users of these products.
Essentially, the vulnerability lies in the router’s function formEasySetupWizard3 and can be exploited remotely by manipulating the host argument to cause a buffer overflow. As these products are no longer supported by the vendor, this discovery underlines the importance of maintaining updated and supported devices.

Vulnerability Summary

CVE ID: CVE-2025-4342
Severity: Critical, CVSS 8.8
Attack Vector: Remote
Privileges Required: None
User Interaction: None
Impact: Potential system compromise and data leakage

Affected Products

Product | Affected Versions

D-Link DIR-600L | Up to 2.07B01

How the Exploit Works

The exploit takes advantage of an overflow buffer in the formEasySetupWizard3 function of D-Link DIR-600L routers. By manipulating the host argument, an attacker can overflow the buffer, leading to undefined behavior in the system. This could potentially allow an attacker to execute arbitrary code, enabling them to compromise the system and possibly leak sensitive data.

Conceptual Example Code

The following is a conceptual example of how a malicious payload might trigger the vulnerability:

POST /formEasySetupWizard3 HTTP/1.1
Host: target.example.com
Content-Type: application/json
{ "host": "A long string that causes buffer overflow..." }

In this example, the “host” argument is filled with a longer string than the buffer can handle, causing an overflow. This could lead to undefined system behavior, potentially opening doors for further exploits.
To mitigate this vulnerability, users are advised to apply vendor patches. In cases where the product is no longer supported by the manufacturer, as is the case with D-Link DIR-600L, users can use a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) as a temporary mitigation strategy. However, the best course of action would be to upgrade to a supported product.