CVE-2025-4149: Netgear EX6200 Buffer Overflow Vulnerability

CVE-2025-4149 Overview

A critical buffer overflow vulnerability has been discovered in Netgear EX6200 firmware version 1.0.3.94. The vulnerability exists in the sub_54014 function, where improper handling of the host argument allows attackers to trigger a buffer overflow condition. This flaw can be exploited remotely over the network, potentially enabling attackers to execute arbitrary code or cause denial of service on affected devices.

The vendor (Netgear) was contacted early about this disclosure but did not respond in any way, leaving affected devices without an official patch.

Critical Impact

Remote attackers can exploit this buffer overflow vulnerability to potentially achieve code execution on Netgear EX6200 wireless range extenders, compromising network security and potentially pivoting to other connected devices.

Affected Products

• Netgear EX6200 Firmware version 1.0.3.94
• Netgear EX6200 Hardware

Discovery Timeline

• 2025-05-01 - CVE-2025-4149 published to NVD
• 2025-05-19 - Last updated in NVD database

Technical Details for CVE-2025-4149

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_54014 function within the Netgear EX6200 firmware, which fails to properly validate the length of the host argument before copying it into a fixed-size buffer.

When an attacker supplies a specially crafted oversized host parameter, the function writes data beyond the allocated buffer boundaries. This memory corruption can overwrite adjacent memory regions, including return addresses on the stack or critical data structures, potentially allowing an attacker to redirect program execution flow.

The vulnerability is particularly concerning because it can be triggered remotely over the network without requiring physical access to the device, and the attacker only needs low-level privileges to exploit it.

Root Cause

The root cause of CVE-2025-4149 is insufficient input validation in the sub_54014 function. The firmware code does not verify the size of the incoming host argument before performing buffer operations. This classic buffer overflow pattern occurs when user-controlled input is copied into a fixed-size memory buffer without boundary checks, allowing data to overflow into adjacent memory regions.

Embedded devices like wireless range extenders often run with limited memory protection mechanisms and may lack modern exploit mitigations such as ASLR or stack canaries, making buffer overflow exploitation more straightforward.

Attack Vector

The attack can be initiated remotely over the network. An attacker with network access to the vulnerable Netgear EX6200 device can send a malicious request containing an oversized host parameter to trigger the buffer overflow. The attack does not require user interaction, making it particularly dangerous in environments where the device's web interface is exposed.

The exploitation mechanism involves:

1. Identifying a vulnerable Netgear EX6200 device running firmware version 1.0.3.94
2. Crafting a request with an oversized host parameter targeting the vulnerable sub_54014 function
3. Sending the malicious request to trigger the buffer overflow
4. Potentially achieving code execution or causing device crash

Technical details regarding the vulnerability mechanism can be found in the GitHub Buffer Overflow Readme and the VulDB #306681 Advisory.

Detection Methods for CVE-2025-4149

Indicators of Compromise

• Unexpected device reboots or crashes on Netgear EX6200 devices
• Unusual network traffic patterns to the device's web management interface
• Oversized HTTP requests containing abnormally long host parameters
• Anomalous behavior or configuration changes on the range extender

Detection Strategies

• Monitor network traffic for requests with unusually large host parameters targeting Netgear EX6200 devices
• Implement intrusion detection rules to identify buffer overflow attack patterns against embedded device web interfaces
• Deploy network segmentation to isolate IoT and networking devices from untrusted network segments
• Review device logs for repeated crashes or unexpected restarts that may indicate exploitation attempts

Monitoring Recommendations

• Enable logging on network firewalls and security appliances to capture traffic to Netgear EX6200 management interfaces
• Use SentinelOne's network visibility capabilities to monitor for suspicious traffic patterns to embedded devices
• Establish baseline behavior for range extender devices and alert on anomalies
• Consider implementing network access controls to restrict which hosts can communicate with device management interfaces

How to Mitigate CVE-2025-4149

Immediate Actions Required

• Restrict network access to the Netgear EX6200 web management interface to trusted IP addresses only
• Disable remote management features if not required for operations
• Place the device behind a firewall that can filter malicious requests
• Monitor for firmware updates from Netgear and apply them immediately when available
• Consider replacing the vulnerable device with a supported model if no patch is forthcoming

Patch Information

No official patch is currently available from Netgear. The vendor was contacted early about this disclosure but did not respond. Users should monitor the Netgear Official Website for future security updates and firmware releases that may address this vulnerability.

Workarounds

• Implement network segmentation to isolate the vulnerable device from untrusted networks
• Configure firewall rules to block external access to the device's management interface
• Use a VPN for remote access rather than exposing the management interface directly
• Consider deploying a web application firewall (WAF) or reverse proxy to filter malicious requests targeting the device

# Example firewall rules to restrict access to Netgear EX6200 management interface
# Replace 192.168.1.100 with your device IP and 192.168.1.0/24 with trusted subnet

# iptables example - allow only trusted subnet access to device
iptables -A FORWARD -d 192.168.1.100 -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
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 -s 192.168.1.0/24 -j ACCEPT
iptables -A FORWARD -d 192.168.1.100 -p tcp --dport 443 -j DROP