CVE-2025-4120: Critical Buffer Overflow Vulnerability in Netgear JWNR2000v2 1.0.0.11

Overview

A severe vulnerability has been unearthed in the firmware of the Netgear JWNR2000v2 1.0.0.11. This vulnerability is critically classified and has been assigned the identifier CVE-2025-4120. With this exploit, cyber attackers can manipulate the host argument to cause a buffer overflow, leading to potential system compromise or data leakage. This vulnerability is of particular concern due to the possibility of remote attack, and the lack of response from the vendor despite early contact about the issue.

Vulnerability Summary

CVE ID: CVE-2025-4120
Severity: Critical (8.8 CVSS Severity Score)
Attack Vector: Remote
Privileges Required: None
User Interaction: None
Impact: Potential system compromise or data leakage

Affected Products

Product | Affected Versions

Netgear JWNR2000v2 | 1.0.0.11

How the Exploit Works

The vulnerability lies in the function sub_4238E8 of the firmware. By manipulating the host argument within this function, an attacker can cause a buffer overflow. This means that the attacker can overwrite the data in memory, causing the system to crash or execute arbitrary code. This can lead to potential system compromise, allowing the attacker to gain unauthorized access to data and resources.

Conceptual Example Code

The following is a conceptual example of how the vulnerability might be exploited. In this example, an HTTP POST request is sent to a vulnerable endpoint with a manipulated host argument, causing a buffer overflow:

POST /sub_4238E8 HTTP/1.1
Host: target.example.com
Content-Type: application/x-www-form-urlencoded
host=AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

In this conceptual example, ‘A’ is used as a placeholder for the malicious payload.

Mitigation Guidance

Until the vendor provides a patch for this critical vulnerability, it is strongly recommended to use a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) as temporary mitigation. These measures can help detect and block attempts to exploit this vulnerability. Users and administrators should also consider disconnecting the affected device from the network until a patch is available to reduce the risk of compromise.
Keep in mind that this is only a temporary solution. The ultimate resolution will be a vendor-supplied patch. Always keep your systems and devices updated with the latest software versions and security patches to protect against such vulnerabilities.