CVE-2025-4147: Netgear Ex6200 Buffer Overflow Vulnerability

CVE-2025-4147 Overview

A critical buffer overflow vulnerability has been identified in Netgear EX6200 firmware version 1.0.3.94. The vulnerability exists within the function sub_47F7C, where improper handling of the host argument allows for memory corruption through a classic buffer overflow attack. This flaw can be exploited remotely over the network by an authenticated attacker, potentially leading to complete device compromise including arbitrary code execution with elevated privileges.

Critical Impact

Remote authenticated attackers can exploit this buffer overflow vulnerability to execute arbitrary code, potentially gaining full control of the Netgear EX6200 Wi-Fi range extender and compromising network security.

Affected Products

• Netgear EX6200 Firmware version 1.0.3.94
• Netgear EX6200 Hardware Device
• All network configurations using the affected firmware version

Discovery Timeline

• May 1, 2025 - CVE-2025-4147 published to NVD
• May 12, 2025 - Last updated in NVD database

Technical Details for CVE-2025-4147

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_47F7C function within the Netgear EX6200 firmware. When processing the host argument, the function fails to properly validate the size of user-supplied input before copying it to a fixed-size buffer. This lack of bounds checking allows an attacker to supply a crafted input that exceeds the allocated buffer size, overwriting adjacent memory regions.

The network-accessible nature of this vulnerability significantly increases its risk profile. An attacker with low-privilege authenticated access to the device can remotely trigger the buffer overflow condition. Successful exploitation could result in complete compromise of confidentiality, integrity, and availability of the affected device, potentially allowing attackers to execute arbitrary code, install persistent backdoors, or pivot to other devices on the network.

Root Cause

The root cause of this vulnerability is the absence of proper input validation and boundary checking in the sub_47F7C function. When handling the host parameter, the firmware directly copies user-controlled data into a stack or heap buffer without verifying that the input length does not exceed the buffer's allocated size. This is a classic example of unsafe memory handling common in embedded systems and IoT firmware where security controls may be limited.

Attack Vector

The attack is network-based and requires low-privilege authentication to the target device. An attacker can remotely craft a malicious request containing an oversized host argument value. When processed by the vulnerable sub_47F7C function, the oversized input overwrites critical memory structures such as return addresses or function pointers. By carefully crafting the overflow payload, an attacker can redirect program execution to arbitrary code, achieving remote code execution on the device.

The vulnerability mechanism involves sending a specially crafted request to the Netgear EX6200 web interface or management service. The host parameter is processed without length validation, allowing the buffer overflow to corrupt adjacent memory. Technical details and proof-of-concept information are available in the GitHub Buffer Overflow Exploit documentation.

Detection Methods for CVE-2025-4147

Indicators of Compromise

• Unusual or unexpected network traffic to/from the Netgear EX6200 device on management ports
• Device instability, unexpected reboots, or unresponsive behavior following network requests
• Modified device configuration or firmware without authorized changes
• Suspicious outbound connections from the range extender to unknown external IP addresses
• Authentication logs showing repeated access attempts or unusual session patterns

Detection Strategies

• Deploy network intrusion detection systems (NIDS) to monitor traffic destined for Netgear EX6200 devices for anomalous patterns or oversized parameter values
• Implement network segmentation to isolate IoT devices and monitor cross-segment traffic for exploitation attempts
• Configure logging on network firewalls to capture and alert on suspicious requests targeting the device's management interface
• Use SentinelOne Singularity to detect and respond to post-exploitation activity if attackers pivot from compromised IoT devices to network endpoints

Monitoring Recommendations

• Regularly audit firmware versions across all Netgear EX6200 devices in your environment
• Monitor device management interface access logs for anomalous authentication patterns or request sizes
• Establish baseline network behavior for IoT devices and alert on deviations
• Review network traffic for indicators of command-and-control communication from compromised devices

How to Mitigate CVE-2025-4147

Immediate Actions Required

• Identify all Netgear EX6200 devices running firmware version 1.0.3.94 in your environment
• Restrict network access to the device management interface to trusted administrator IP addresses only
• Disable remote management features if not required for operations
• Implement network segmentation to isolate vulnerable devices from critical network assets
• Monitor for vendor security advisories and firmware updates from Netgear

Patch Information

As of the last update, Netgear has not responded to responsible disclosure attempts regarding this vulnerability. No official security patch is currently available from the vendor. Organizations should monitor the Netgear Support website for future firmware updates that address this issue. Additional technical details are tracked in VulDB #306679.

Workarounds

• Implement strict access control lists (ACLs) to limit which IP addresses can access the device's web management interface
• Place affected devices behind a firewall that filters incoming traffic and blocks requests with anomalous parameter sizes
• Disable the device's remote management interface and require physical or local network access for administration
• Consider replacing vulnerable devices with supported hardware that receives regular security updates
• Use network monitoring tools to detect and alert on potential exploitation attempts targeting these devices

# Example: Restrict management access using firewall rules
# Block external access to Netgear EX6200 management port
iptables -A INPUT -p tcp --dport 80 -s !192.168.1.0/24 -j DROP
iptables -A INPUT -p tcp --dport 443 -s !192.168.1.0/24 -j DROP

# Allow management only from specific admin workstation
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.100 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.100 -j ACCEPT