CVE-2025-4116: Netgear JWNR2000 Buffer Overflow Vulnerability

CVE-2025-4116 Overview

A critical buffer overflow vulnerability has been discovered in the Netgear JWNR2000v2 wireless router firmware version 1.0.0.11. The vulnerability exists within the get_cur_lang_ver function, where improper handling of the host argument allows an attacker 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 was contacted regarding this disclosure but did not respond, leaving affected users without an official patch or guidance from Netgear.

Critical Impact

Remote attackers can exploit this buffer overflow vulnerability to potentially achieve code execution or cause system instability on Netgear JWNR2000v2 routers, compromising network security for connected devices.

Affected Products

• Netgear JWNR2000v2 Hardware
• Netgear JWNR2000 Firmware version 1.0.0.11

Discovery Timeline

• April 30, 2025 - CVE-2025-4116 published to NVD
• May 16, 2025 - Last updated in NVD database

Technical Details for CVE-2025-4116

Vulnerability Analysis

This vulnerability falls 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 get_cur_lang_ver function in the Netgear JWNR2000v2 firmware fails to properly validate the length of user-supplied input through the host argument before copying it into a fixed-size memory buffer.

When an attacker provides an oversized or malformed host value, the function copies data beyond the allocated buffer boundaries, corrupting adjacent memory regions. This memory corruption can lead to control flow hijacking, allowing an attacker to redirect program execution to attacker-controlled code or cause the device to crash.

The vulnerability is particularly dangerous because it can be exploited remotely over the network without requiring physical access to the device. An authenticated attacker with low privileges can leverage this flaw to potentially gain complete control over the router.

Root Cause

The root cause of this vulnerability is the absence of proper bounds checking in the get_cur_lang_ver function. The function processes the host argument without validating that the input data fits within the destination buffer's allocated size. This classic buffer overflow pattern results from using unsafe memory copy operations that do not enforce length restrictions, allowing attackers to write beyond buffer boundaries and corrupt critical memory structures including return addresses and function pointers.

Attack Vector

The attack can be launched remotely over the network. An attacker needs to craft a malicious request containing an oversized host parameter targeting the vulnerable get_cur_lang_ver function. Upon processing this request, the router's firmware will copy the malicious input into memory, overflowing the buffer and potentially allowing the attacker to:

1. Overwrite return addresses to redirect execution flow
2. Inject and execute arbitrary shellcode
3. Cause denial of service by crashing the device
4. Gain persistent access to the router's operating system

The vulnerability requires low-level authentication but no user interaction, making it relatively straightforward to exploit once network access is obtained.

Technical details and proof-of-concept information can be found in the GitHub PoC Repository and VulDB #306596.

Detection Methods for CVE-2025-4116

Indicators of Compromise

• Unexpected router reboots or crashes without apparent cause
• Unusual network traffic patterns originating from or destined to the router's management interface
• Modified router configurations or unauthorized administrative accounts
• Suspicious outbound connections from the router to unknown external IP addresses

Detection Strategies

• Monitor network traffic for anomalous HTTP requests containing oversized host parameters targeting the router's web interface
• Implement intrusion detection rules to identify buffer overflow exploitation attempts against embedded device management interfaces
• Review router logs for authentication anomalies or repeated failed access attempts
• Deploy network segmentation to limit exposure of router management interfaces

Monitoring Recommendations

• Enable logging on the router if available and forward logs to a centralized SIEM for analysis
• Conduct periodic firmware integrity checks to detect unauthorized modifications
• Monitor for unusual CPU or memory utilization patterns on the affected device
• Implement network-based anomaly detection to identify exploitation attempts

How to Mitigate CVE-2025-4116

Immediate Actions Required

• Restrict access to the router's web management interface to trusted internal networks only
• Disable remote management features if enabled
• Place the router behind a firewall that blocks unsolicited inbound connections
• Consider replacing the Netgear JWNR2000v2 with a supported router model that receives security updates
• Implement network segmentation to isolate the vulnerable device

Patch Information

No official patch is currently available from Netgear. The vendor was contacted about this vulnerability but did not respond. Users should monitor the Netgear Official Website for any future firmware updates, though the JWNR2000v2 is a legacy product that may no longer receive support.

Given the lack of vendor response and the device's age, the recommended course of action is to replace the affected router with a currently supported model.

Workarounds

• Disable the web management interface entirely if not required for operations
• Implement strict access control lists (ACLs) to limit which IP addresses can reach the router's management interface
• Use a VPN to access the router's management interface rather than exposing it directly
• Consider deploying a secondary firewall or security appliance in front of the vulnerable router

# Example: Restrict management interface access via firewall rules
# Block external access to router management port (example using iptables on upstream device)
iptables -A FORWARD -d 192.168.1.1 -p tcp --dport 80 -j DROP
iptables -A FORWARD -d 192.168.1.1 -p tcp --dport 443 -j DROP

# Allow only trusted management stations
iptables -A FORWARD -s 192.168.1.100 -d 192.168.1.1 -p tcp --dport 80 -j ACCEPT