CVE-2025-4148 Overview
CVE-2025-4148 is a buffer overflow vulnerability in the Netgear EX6200 WiFi range extender running firmware version 1.0.3.94. The flaw resides in the function sub_503FC, where manipulation of the host argument triggers memory corruption. Attackers can exploit the issue remotely over the network without user interaction. The vendor was contacted prior to public disclosure but did not respond, and no patch is currently available. The vulnerability is tracked in VulDB as entry #306680 and maps to [CWE-119] (improper restriction of operations within the bounds of a memory buffer) and [CWE-120] (classic buffer overflow).
Critical Impact
Remote attackers with low privileges can corrupt memory on affected EX6200 devices, potentially leading to arbitrary code execution or denial of service on network infrastructure.
Affected Products
- Netgear EX6200 hardware appliance
- Netgear EX6200 firmware version 1.0.3.94
- Web management interface component implementing sub_503FC
Discovery Timeline
- 2025-05-01 - CVE-2025-4148 published to NVD
- 2025-05-12 - Last updated in NVD database
Technical Details for CVE-2025-4148
Vulnerability Analysis
The vulnerability exists in the sub_503FC function within the Netgear EX6200 firmware. The function processes the host argument without enforcing proper bounds on the destination buffer. When an attacker supplies an oversized value, the write operation exceeds the allocated buffer and overwrites adjacent memory regions. This classic buffer overflow pattern can corrupt control data such as saved return addresses or function pointers on devices that lack memory protections common in embedded MIPS or ARM systems. The attack is network-reachable and requires low-level privileges on the device interface.
Root Cause
The root cause is missing bounds validation on the host parameter prior to a memory copy operation inside sub_503FC. The firmware trusts attacker-controlled input length, which falls under both [CWE-119] and [CWE-120]. Embedded consumer networking devices frequently lack stack canaries, ASLR, and non-executable stacks, making such overflows directly exploitable.
Attack Vector
An attacker reaches the vulnerable code path by sending a crafted request containing an oversized host value to the EX6200 management interface. Because the device is a WiFi range extender, exposure on the local network or any reachable management surface is sufficient. Successful exploitation may corrupt process memory and lead to code execution or service crash, disrupting wireless coverage and providing a foothold inside the network segment.
No verified proof-of-concept code is reproduced here. Technical details on the vulnerable function and parameter handling are documented in the GitHub PoC Repository and VulDB entry #306680.
Detection Methods for CVE-2025-4148
Indicators of Compromise
- Unexpected reboots, crashes, or web management interface unavailability on EX6200 devices running firmware 1.0.3.94.
- HTTP or HTTPS requests to the device management interface containing abnormally long host header or parameter values.
- New or unauthorized configuration changes on the range extender, including DNS, routing, or administrative credentials.
Detection Strategies
- Inspect inbound traffic to EX6200 management interfaces for requests with oversized host fields that exceed typical hostname length (greater than 253 characters).
- Monitor device syslog, if forwarded, for watchdog resets, segmentation faults, or repeated HTTP daemon restarts indicating exploitation attempts.
- Correlate Layer 2 and Layer 3 anomalies originating from the extender, such as unexpected outbound connections, with management-plane request anomalies.
Monitoring Recommendations
- Forward router and extender logs into a centralized log platform and alert on repeated crashes of the web management process.
- Network detection rules should flag HTTP requests targeting EX6200 device IPs with parameter lengths exceeding defined thresholds.
- Track firmware versions across the fleet and alert when devices report version 1.0.3.94 with no upgrade path available.
How to Mitigate CVE-2025-4148
Immediate Actions Required
- Restrict access to the EX6200 web management interface to a dedicated management VLAN or trusted administrative hosts only.
- Disable remote management features and ensure the device is not exposed to the WAN or untrusted wireless segments.
- Inventory all Netgear EX6200 devices and confirm firmware versions; treat any unit on 1.0.3.94 as vulnerable.
Patch Information
Netgear has not issued a security advisory or patch for CVE-2025-4148 at the time of publication. The vendor did not respond to the original disclosure attempt documented in VulDB entry #306680. Monitor the Netgear Official Site for future firmware releases addressing the sub_503FC buffer overflow. If no patch becomes available within an acceptable risk window, plan replacement of the device with a supported model.
Workarounds
- Segment EX6200 devices on an isolated VLAN with strict ACLs preventing management access from user subnets.
- Place the device behind a firewall rule that blocks inbound HTTP and HTTPS to the management interface from all but explicitly trusted addresses.
- Replace end-of-support or unpatched EX6200 units with current Netgear models or alternative range extenders that receive active security updates.
# Example: restrict management access to EX6200 via upstream firewall (iptables)
iptables -A FORWARD -d <EX6200_IP> -p tcp --dport 80 -s <ADMIN_SUBNET> -j ACCEPT
iptables -A FORWARD -d <EX6200_IP> -p tcp --dport 443 -s <ADMIN_SUBNET> -j ACCEPT
iptables -A FORWARD -d <EX6200_IP> -p tcp --dport 80 -j DROP
iptables -A FORWARD -d <EX6200_IP> -p tcp --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
