CVE-2025-4121: Netgear JWNR2000v2 Firmware RCE Vulnerability

CVE-2025-4121 Overview

A critical command injection vulnerability has been identified in the Netgear JWNR2000v2 wireless router running firmware version 1.0.0.11. The vulnerability exists within the cmd_wireless function, where improper handling of the host argument allows remote attackers to inject and execute arbitrary commands on the affected device. This flaw can be exploited remotely over the network by authenticated attackers, potentially leading to complete compromise of the router and the network it manages.

Critical Impact

Remote attackers can execute arbitrary system commands on vulnerable Netgear JWNR2000v2 routers, potentially gaining full control of the device, intercepting network traffic, or using the compromised router as a pivot point for further attacks on the internal network.

Affected Products

• Netgear JWNR2000v2 Firmware version 1.0.0.11
• Netgear JWNR2000v2 Hardware

Discovery Timeline

• April 30, 2025 - CVE-2025-4121 published to NVD
• May 13, 2025 - Last updated in NVD database

Note: The vendor (Netgear) was contacted early about this disclosure but did not respond in any way.

Technical Details for CVE-2025-4121

Vulnerability Analysis

This command injection vulnerability (CWE-77) stems from insufficient input validation in the cmd_wireless function of the Netgear JWNR2000v2 firmware. The function processes user-supplied input through the host parameter without proper sanitization, allowing attackers to inject shell metacharacters and arbitrary commands that are then executed with the privileges of the web server process on the router.

The attack can be launched remotely over the network and requires low-privilege authentication to exploit. The vulnerability affects the confidentiality, integrity, and availability of the device, though the immediate impact is limited to the vulnerable router itself without direct propagation to connected systems.

Root Cause

The root cause of CVE-2025-4121 is a classic injection flaw (CWE-74) where user-controlled input is passed to a system shell or command execution function without adequate validation or escaping. The cmd_wireless function fails to sanitize special characters in the host argument, allowing command delimiters (such as semicolons, pipes, or backticks) to break out of the intended command context and execute attacker-controlled instructions.

Attack Vector

The vulnerability is exploitable over the network by authenticated users. An attacker with valid credentials to the router's web management interface can craft malicious requests containing shell metacharacters in the host parameter. When the cmd_wireless function processes this input, the injected commands are executed on the underlying operating system.

The attack flow typically involves:

1. Authenticating to the router's web interface (requires low privileges)
2. Sending a crafted request to the vulnerable function with malicious payload in the host parameter
3. The injected commands execute with the router's system privileges

For technical details and proof-of-concept information, refer to the GitHub Command Injection PoC documentation.

Detection Methods for CVE-2025-4121

Indicators of Compromise

• Unusual outbound network connections originating from the router to unknown external IP addresses
• Unexpected processes running on the router that are not part of normal firmware operation
• Modified configuration files or new user accounts created on the router
• Log entries showing malformed or suspicious requests to the web management interface containing shell metacharacters

Detection Strategies

• Monitor network traffic for unusual patterns from router management interfaces, particularly HTTP requests containing shell metacharacters (;, |, $(), backticks) in parameter values
• Implement network-based intrusion detection rules to identify command injection attempts targeting Netgear devices
• Review router access logs for authentication anomalies and unusual administrative actions
• Deploy SentinelOne Singularity to monitor network endpoints for indicators of router compromise and lateral movement attempts

Monitoring Recommendations

• Enable and regularly review router access logs for signs of exploitation attempts
• Monitor for DNS or routing changes on the network that could indicate router compromise
• Implement network segmentation to limit the impact if the router is compromised
• Use SentinelOne network visibility features to detect anomalous traffic patterns from infrastructure devices

How to Mitigate CVE-2025-4121

Immediate Actions Required

• Restrict access to the router's web management interface to trusted internal networks only
• Disable remote management capabilities if not required for operations
• Change default credentials and use strong, unique passwords for router administration
• Consider replacing the affected device with a newer model that receives active security updates

Patch Information

At the time of this writing, Netgear has not responded to disclosure attempts regarding this vulnerability. No official patch is currently available for firmware version 1.0.0.11 of the JWNR2000v2. Users should monitor the Netgear Official Website for security advisories and firmware updates. Given the end-of-life status of this device model, users are strongly encouraged to consider upgrading to a supported router model.

Additional technical information is available through VulDB CTI Report #306601 and VulDB #306601.

Workarounds

• Place the router behind a firewall that restricts access to the management interface from untrusted networks
• Use ACLs (Access Control Lists) to limit which IP addresses can access the router's administrative functions
• Implement network monitoring to detect and alert on potential exploitation attempts
• Consider deploying a VPN for any remote management needs rather than exposing the management interface directly

# Example: Restrict management access using firewall rules (iptables on upstream device)
# Block external access to router management port (typically 80/443)
iptables -A FORWARD -d <ROUTER_IP> -p tcp --dport 80 -j DROP
iptables -A FORWARD -d <ROUTER_IP> -p tcp --dport 443 -j DROP

# Allow only trusted management IP
iptables -I FORWARD -s <TRUSTED_ADMIN_IP> -d <ROUTER_IP> -p tcp --dport 80 -j ACCEPT