CVE-2025-4146: Netgear EX6200 Firmware RCE Vulnerability

CVE-2025-4146 Overview

A critical buffer overflow vulnerability has been discovered in the Netgear EX6200 WiFi Range Extender firmware version 1.0.3.94. The vulnerability exists in the sub_41940 function, where improper handling of the host argument allows remote attackers to trigger a buffer overflow condition. This firmware vulnerability enables remote exploitation over the network and could lead to complete device compromise.

Critical Impact

Remote attackers can exploit this buffer overflow to potentially execute arbitrary code, cause denial of service, or gain unauthorized control over the affected Netgear EX6200 device. The vendor was contacted about this disclosure but did not respond.

Affected Products

• Netgear EX6200 WiFi Range Extender
• Netgear EX6200 Firmware version 1.0.3.94

Discovery Timeline

• 2025-05-01 - CVE-2025-4146 published to NVD
• 2025-05-12 - Last updated in NVD database

Technical Details for CVE-2025-4146

Vulnerability Analysis

This vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer) and CWE-120 (Buffer Copy without Checking Size of Input). The flaw resides in the sub_41940 function within the Netgear EX6200 firmware. When processing the host argument (specifically related to SMB host name handling), the function fails to properly validate the length of user-supplied input before copying it into a fixed-size buffer.

The vulnerability can be exploited remotely without user interaction, though it requires low-level privileges. Successful exploitation could allow an attacker to corrupt memory, potentially leading to arbitrary code execution with the privileges of the firmware process, or cause a denial of service condition on the device.

Root Cause

The root cause stems from classic buffer overflow conditions where the sub_41940 function does not perform adequate bounds checking on the host parameter. When an attacker supplies an oversized input value, the data overflows beyond the allocated buffer boundaries, overwriting adjacent memory regions. This is a common vulnerability pattern in embedded device firmware where secure coding practices and memory-safe functions are not consistently applied.

Attack Vector

The attack can be launched remotely over the network. An attacker with network access to the Netgear EX6200 device can craft malicious requests containing an oversized host parameter value. The exploitation does not require user interaction, making it particularly dangerous for devices exposed to untrusted networks or the internet.

Technical details and proof-of-concept information are available in the GitHub PoC Repository.

Detection Methods for CVE-2025-4146

Indicators of Compromise

• Unusual network traffic patterns targeting the Netgear EX6200 management interfaces
• Device instability, unexpected reboots, or unresponsive behavior indicating memory corruption
• Anomalous log entries related to SMB configuration or host name processing
• Network connections to or from the device to unexpected external IP addresses

Detection Strategies

• Monitor network traffic for unusually large or malformed requests to the Netgear EX6200 device interfaces
• Implement intrusion detection rules to identify buffer overflow exploitation attempts targeting embedded devices
• Deploy network segmentation to isolate IoT and network infrastructure devices from untrusted network segments
• Use SentinelOne Singularity to monitor for anomalous behavior patterns on network segments containing vulnerable devices

Monitoring Recommendations

• Enable logging on network firewalls and security appliances to capture traffic to and from Netgear devices
• Regularly audit device configurations and compare against known-good baselines
• Monitor for firmware integrity changes or unauthorized modifications to device settings
• Implement network-based anomaly detection to identify exploitation attempts

How to Mitigate CVE-2025-4146

Immediate Actions Required

• Restrict network access to the Netgear EX6200 management interface to trusted IP addresses only
• Isolate affected devices on a separate network segment with strict access controls
• Consider replacing the device if no firmware update is available, as the vendor did not respond to disclosure
• Monitor the Netgear Official Website for potential security updates

Patch Information

As of the last NVD update on 2025-05-12, no patch has been released by Netgear. The vendor was contacted early about this disclosure but did not respond. Organizations should monitor Netgear's security advisories for any future firmware updates that address this vulnerability.

Additional technical details are available via VulDB #306678.

Workarounds

• Disable remote management access to the Netgear EX6200 device
• Implement firewall rules to block external access to the device's management interfaces
• Use a VPN to access the device management interface rather than exposing it directly
• Consider decommissioning the affected device if it is exposed to untrusted networks and no patch becomes available

# Example firewall rule to restrict access to Netgear device management (adjust IP addresses as needed)
# Block external access to common management ports
iptables -A FORWARD -d 192.168.1.100 -p tcp --dport 80 -j DROP
iptables -A FORWARD -d 192.168.1.100 -p tcp --dport 443 -j DROP
iptables -A FORWARD -d 192.168.1.100 -p tcp --dport 23 -j DROP

# Allow only trusted management subnet
iptables -A FORWARD -s 192.168.10.0/24 -d 192.168.1.100 -p tcp --dport 80 -j ACCEPT