CVE-2025-5441: Linksys RE9000 Firmware RCE Vulnerability

CVE-2025-5441 Overview

A critical OS command injection vulnerability has been identified in multiple Linksys range extender devices. This vulnerability affects the setDeviceURL function within the /goform/setDeviceURL endpoint, where improper sanitization of the DeviceURL argument allows remote attackers to inject and execute arbitrary operating system commands. The exploit has been publicly disclosed, and the vendor was contacted about this vulnerability but did not respond.

Critical Impact

Remote attackers with low privileges can exploit this command injection vulnerability to execute arbitrary OS commands on affected Linksys range extenders, potentially leading to complete device compromise, network infiltration, and use of the device in botnet operations.

Affected Products

• Linksys RE6500 Firmware version 1.0.013.001
• Linksys RE6250 Firmware version 1.0.04.001
• Linksys RE6300 Firmware version 1.2.07.001
• Linksys RE6350 Firmware version 1.0.04.001
• Linksys RE7000 Firmware version 1.1.05.003
• Linksys RE9000 Firmware version 1.0.04.002

Discovery Timeline

• 2025-06-02 - CVE-2025-5441 published to NVD
• 2025-06-25 - Last updated in NVD database

Technical Details for CVE-2025-5441

Vulnerability Analysis

This vulnerability is classified under CWE-77 (Improper Neutralization of Special Elements used in a Command) and CWE-78 (Improper Neutralization of Special Elements used in an OS Command). The core issue lies in the setDeviceURL function's failure to properly validate and sanitize user-supplied input before passing it to system shell commands.

When a user submits a request to the /goform/setDeviceURL endpoint, the DeviceURL parameter value is processed without adequate input filtering. This allows an attacker to embed shell metacharacters and command sequences within the parameter, which are then interpreted and executed by the underlying operating system with the privileges of the web server process—typically root on embedded devices like these range extenders.

The network-accessible nature of this vulnerability means attackers can exploit it remotely, though authentication with low-level privileges appears to be required. Once exploited, attackers gain the ability to execute commands with full system privileges, enabling complete device takeover.

Root Cause

The root cause of CVE-2025-5441 is insufficient input validation in the setDeviceURL function. The firmware fails to sanitize special shell characters (such as ;, |, &, $(), and backticks) from the DeviceURL parameter before incorporating it into system command execution. This classic command injection pattern allows attackers to break out of the intended command context and execute arbitrary commands.

Attack Vector

The attack is initiated remotely over the network against the device's web management interface. An attacker with valid credentials (even low-privileged ones) can send a crafted HTTP request to the /goform/setDeviceURL endpoint. By injecting shell metacharacters and malicious commands within the DeviceURL parameter, the attacker can achieve arbitrary command execution on the target device.

A typical attack scenario involves:

1. Accessing the Linksys range extender's web interface
2. Authenticating with any valid user credentials
3. Sending a malicious POST request to /goform/setDeviceURL with a crafted DeviceURL value containing injected commands
4. The injected commands execute on the device with elevated privileges

For detailed technical analysis and proof-of-concept information, refer to the GitHub Vulnerability Documentation and VulDB CVE-310780 Analysis.

Detection Methods for CVE-2025-5441

Indicators of Compromise

• Unusual HTTP POST requests to /goform/setDeviceURL containing shell metacharacters (;, |, &, $(, backticks)
• Unexpected outbound network connections from range extender devices to unknown IP addresses
• Anomalous process spawning or command execution patterns in device logs
• Changes to device configuration files or firmware without administrator action

Detection Strategies

• Implement network intrusion detection rules to monitor for HTTP traffic targeting /goform/setDeviceURL with suspicious payload patterns
• Deploy web application firewall rules to block requests containing common command injection payloads directed at affected Linksys devices
• Monitor device management interface access logs for requests with unusual DeviceURL parameter values
• Use network segmentation monitoring to detect any unexpected traffic originating from IoT/network devices

Monitoring Recommendations

• Enable comprehensive logging on network firewalls and intrusion detection systems for traffic to and from Linksys range extenders
• Implement network behavior analysis to detect anomalous communication patterns from affected devices
• Regularly audit device configurations to identify unauthorized changes that may indicate compromise
• Consider isolating range extenders on a separate network segment with restricted access

How to Mitigate CVE-2025-5441

Immediate Actions Required

• Restrict network access to the web management interface of affected Linksys range extenders to trusted IP addresses only
• Disable remote management features if not required for operations
• Implement strong firewall rules to prevent unauthorized access to the device's administrative interfaces
• Consider network segmentation to isolate vulnerable devices from critical network assets

Patch Information

At the time of this publication, Linksys has not released a security patch for CVE-2025-5441. The vendor was contacted about this vulnerability but did not respond. Users should monitor the Linksys Official Website for any future firmware updates that may address this issue. Until a patch is available, implementing the recommended workarounds is essential to reduce risk exposure.

Workarounds

• Configure access control lists (ACLs) on your network firewall to restrict access to the range extender's management interface to specific trusted IP addresses
• Disable the web management interface if it is not actively needed for device administration
• Place affected devices on an isolated VLAN with limited connectivity to minimize the potential blast radius of a compromise
• Consider replacing affected devices with models from vendors with active security support if no patch becomes available

# Example firewall rule to restrict management interface access (iptables)
# Allow management access only from trusted admin workstation
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.100 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.100 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP