CVE-2025-4148: Netgear EX6200 Buffer Overflow Vulnerability

CVE-2025-4148 Overview

A critical buffer overflow vulnerability has been identified in the Netgear EX6200 WiFi Range Extender firmware version 1.0.3.94. The vulnerability exists in the function sub_503FC, where improper handling of the host argument allows attackers to trigger a buffer overflow condition. This firmware-level vulnerability in a consumer networking device poses significant risks as it can be exploited remotely over the network.

Critical Impact

Remote attackers can exploit this buffer overflow to potentially execute arbitrary code or cause denial of service on affected Netgear EX6200 devices, compromising network security infrastructure.

Affected Products

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

Discovery Timeline

• May 1, 2025 - CVE-2025-4148 published to NVD
• May 12, 2025 - Last updated in NVD database

Technical Details for CVE-2025-4148

Vulnerability Analysis

This vulnerability represents a classic buffer overflow condition (CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer, CWE-120: Buffer Copy without Checking Size of Input) in embedded firmware. The vulnerable function sub_503FC fails to properly validate the length of the host argument before copying it into a fixed-size buffer. When an attacker supplies an overly long input value for the host parameter, the data overflows the allocated buffer, potentially overwriting adjacent memory regions including return addresses or function pointers.

The network-accessible nature of this vulnerability is particularly concerning as it can be exploited without physical access to the device. Attackers with low-privilege network access can craft malicious requests containing oversized host values to trigger the overflow condition.

Root Cause

The root cause of this vulnerability lies in the sub_503FC function's failure to implement proper bounds checking when processing the host argument. The function copies user-supplied input directly into a memory buffer without validating that the input length does not exceed the buffer's allocated size. This is a common vulnerability pattern in embedded systems where memory-safe programming practices are often overlooked due to resource constraints.

Attack Vector

The attack can be launched remotely over the network. An authenticated attacker can exploit this vulnerability by sending specially crafted requests to the vulnerable device containing malicious host parameter values. The manipulation of the host argument with excessive data triggers the buffer overflow, which can lead to:

• Corruption of adjacent memory structures
• Overwriting of return addresses on the stack
• Potential arbitrary code execution with device privileges
• Device crash resulting in denial of service

Technical details and proof-of-concept information are available in the GitHub PoC Repository. The vendor was contacted about this disclosure but did not respond.

Detection Methods for CVE-2025-4148

Indicators of Compromise

• Unusual network traffic patterns targeting the EX6200 management interface
• Device crashes or unexpected reboots without administrative action
• Anomalous HTTP requests containing oversized host parameter values
• Evidence of exploitation attempts in device logs showing malformed requests

Detection Strategies

• Monitor network traffic for abnormally large HTTP request parameters targeting Netgear devices
• Implement intrusion detection rules to identify buffer overflow exploitation patterns
• Deploy network segmentation to isolate IoT and network extension devices
• Use SentinelOne Singularity to detect anomalous behavior from network devices

Monitoring Recommendations

• Enable logging on network boundary devices to capture traffic to/from the EX6200
• Implement network-based anomaly detection for embedded device communications
• Regularly audit device firmware versions against known vulnerable releases
• Monitor for unexpected outbound connections from network infrastructure devices

How to Mitigate CVE-2025-4148

Immediate Actions Required

• Isolate affected Netgear EX6200 devices from untrusted network segments
• Restrict management interface access to trusted administrative networks only
• Disable remote management features if not required
• Monitor for any signs of exploitation or compromise
• Consider replacing affected devices with alternatives if no patch becomes available

Patch Information

No patch is currently available from Netgear. According to the vulnerability disclosure, the vendor was contacted early about this issue but did not respond. Users should monitor the Netgear Support Website for potential firmware updates. Additional vulnerability details are available through VulDB #306680.

Workarounds

• Implement network access controls to limit who can reach the device management interface
• Place affected devices behind a firewall with strict ingress filtering
• Disable unnecessary network services on the EX6200 device
• Use VLANs to segment IoT and network extension devices from critical systems
• Consider deploying an alternative WiFi range extender that receives active security support

# Example network isolation configuration (firewall rules)
# Block external access to EX6200 management interface
# Adjust IP addresses based on your network configuration
iptables -A FORWARD -d 192.168.1.x -p tcp --dport 80 -j DROP
iptables -A FORWARD -d 192.168.1.x -p tcp --dport 443 -j DROP