Author: Ameeba

Overview

In our continuously evolving digital world, security vulnerabilities pose a significant threat to both individuals and businesses alike. One such recent discovery is the critical vulnerability identified in Netgear EX6120 1.0.0.68, a widely used network product. The vulnerability, classified as CVE-2025-4139, has been found in the fwAcosCgiInbound function and can lead to a buffer overflow. This vulnerability has substantial implications, including potential system compromise and data leakage.
The vulnerability CVE-2025-4139 matters because it can be exploited remotely, putting a vast number of systems at risk. Unfortunately, the vendor has been unresponsive to this disclosure, making immediate mitigation efforts crucial for all affected systems.

Vulnerability Summary

CVE ID: CVE-2025-4139
Severity: Critical (8.8/10 CVSS Score)
Attack Vector: Remote
Privileges Required: None
User Interaction: None
Impact: System compromise and potential data leakage

Affected Products

Product | Affected Versions

Netgear EX6120 | 1.0.0.68

How the Exploit Works

The exploit works by manipulating the ‘host’ argument in the fwAcosCgiInbound function of the Netgear EX6120 1.0.0.68. This manipulation allows a buffer overflow to occur. A buffer overflow is a situation where more data is written into a fixed-length buffer than the buffer can handle. This overflow in memory can overwrite adjacent memory locations and cause unpredictable system behavior, including crashes, incorrect execution, and most critically, the execution of malicious code.

Conceptual Example Code

Below is a conceptual example illustrating how the vulnerability might be exploited. This is a sample HTTP request that includes a malicious payload designed to trigger the buffer overflow.

POST /fwAcosCgiInbound HTTP/1.1
Host: vulnerable-router.example.com
Content-Type: application/json
{ "host": "..." } // Insert malicious payload here that overflows the buffer

It should be noted that this is a conceptual example. Real-world exploits may be more complex and require deeper understanding of the system’s internals.

Countermeasures and Mitigation

Until the vendor releases a patch, it’s advisable to use a Web Application Firewall (WAF) or Intrusion Detection System (IDS) as a temporary mitigation method. These measures can detect and prevent the exploitation of the vulnerability. It is always important to keep systems up to date with the latest security patches and updates to ensure maximum protection against such threats.

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.

Overview

A critical vulnerability, identified as CVE-2025-4116, has been discovered in Netgear JWNR2000v2 1.0.0.11. This vulnerability specifically targets the function get_cur_lang_ver and can be exploited remotely. Due to its severity, this issue is of significant concern to those utilizing the affected product, as it poses a serious threat to system integrity, potentially leading to system compromise or data leakage.
This vulnerability is particularly alarming due to its critical rating and the fact that the vendor has been unresponsive to early disclosure attempts. Therefore, all users of the affected Netgear product are urged to take immediate action to mitigate the potential risks associated with this vulnerability.

Vulnerability Summary

CVE ID: CVE-2025-4116
Severity: Critical, CVSS Score 8.8
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 resides in the get_cur_lang_ver function of the Netgear JWNR2000v2 1.0.0.11 router. It can be exploited through manipulation of the host argument, which triggers a buffer overflow. This overflow can lead to unpredictable behavior, such as crashes, code execution, or an information leak. The attack can be launched remotely, and no user interaction is required, making it particularly dangerous.

Conceptual Example Code

The following is a conceptual example of how the vulnerability might be exploited. This example uses a malformed HTTP request to trigger the buffer overflow.

POST /get_cur_lang_ver HTTP/1.1
Host: target.example.com
Content-Type: application/json
{ "host": "AAAAAAAAAAAAAAA... [insert thousands of 'A's to cause a buffer overflow]" }

This request could potentially cause the affected router to crash or execute arbitrary code, leading to system compromise.

Mitigation Measures

Given the critical nature of this vulnerability, it is recommended that users of the affected product apply vendor patches as soon as they become available. In the meantime, or in the absence of vendor patches, users can mitigate the vulnerability by employing Web Application Firewalls (WAF) or Intrusion Detection Systems (IDS) to monitor and filter out malicious traffic. Additionally, users should consider isolating the affected device from the rest of the network to minimize potential damage.