CVE-2025-5447: Linksys RE9000 Firmware RCE Vulnerability

CVE-2025-5447 Overview

A critical OS command injection vulnerability has been discovered in multiple Linksys range extender models. This vulnerability affects the ssid1MACFilter function located in the /goform/ssid1MACFilter file. Improper handling of the apselect_%d and newap_text_%d parameters allows remote authenticated attackers to inject and execute arbitrary operating system commands on the affected devices. The exploit has been publicly disclosed, and the vendor was contacted about this issue but did not respond.

Critical Impact

Remote authenticated attackers can execute arbitrary commands on vulnerable Linksys range extenders, potentially leading to complete device compromise, network pivoting, and unauthorized access to connected network resources.

Affected Products

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

Discovery Timeline

• 2025-06-02 - CVE-2025-5447 published to NVD
• 2025-07-02 - Last updated in NVD database

Technical Details for CVE-2025-5447

Vulnerability Analysis

This vulnerability stems from insufficient input validation in the web management interface of affected Linksys range extenders. The ssid1MACFilter function processes user-supplied input through the apselect_%d and newap_text_%d parameters without adequate sanitization. When these parameters are passed to system-level commands, an attacker can craft malicious input that breaks out of the intended command context and executes arbitrary OS commands.

The 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). This indicates that the application fails to properly neutralize shell metacharacters and special elements before incorporating user input into system commands.

Root Cause

The root cause of this vulnerability is the direct use of unsanitized user input in system command execution. The ssid1MACFilter function in /goform/ssid1MACFilter accepts parameters that are intended to configure MAC filtering settings. However, the application fails to validate or escape special characters in the apselect_%d and newap_text_%d parameters before passing them to the underlying operating system shell. This allows attackers to inject shell metacharacters (such as ;, |, &&, or backticks) to chain additional commands.

Attack Vector

The attack can be initiated remotely over the network by any authenticated user with access to the device's web management interface. An attacker needs to:

1. Authenticate to the Linksys range extender's web interface (typically using default or compromised credentials)
2. Navigate to or directly access the /goform/ssid1MACFilter endpoint
3. Submit a crafted request with malicious command injection payloads in the apselect_%d or newap_text_%d parameters
4. The injected commands execute with the privileges of the web server process, typically root on embedded devices

The vulnerability's exploitation mechanism involves injecting shell metacharacters followed by arbitrary commands. On embedded Linux devices like these range extenders, successful exploitation typically grants root-level access, enabling attackers to modify firmware, exfiltrate data, pivot to other network devices, or establish persistent backdoors.

For detailed technical information about the vulnerability, refer to the GitHub Vulnerability Document and VulDB Entry #310786.

Detection Methods for CVE-2025-5447

Indicators of Compromise

• Unexpected outbound network connections from the range extender to unknown IP addresses
• Unauthorized configuration changes in the device's MAC filtering settings
• Unusual HTTP POST requests to /goform/ssid1MACFilter containing shell metacharacters (;, |, &&, `)
• Presence of unauthorized files or processes on the device's filesystem
• Device reboots or performance degradation without administrative action

Detection Strategies

• Monitor network traffic for HTTP requests to /goform/ssid1MACFilter containing suspicious characters or command patterns
• Implement web application firewall (WAF) rules to detect command injection patterns in form parameters
• Review device logs for repeated authentication attempts followed by configuration changes
• Deploy network intrusion detection signatures targeting OS command injection payloads in HTTP traffic

Monitoring Recommendations

• Enable logging on the Linksys device if available and forward logs to a centralized SIEM
• Monitor for DNS queries or network connections originating from the range extender to unexpected destinations
• Implement anomaly detection for HTTP request patterns to the device's web interface
• Regularly audit device configurations for unauthorized changes

How to Mitigate CVE-2025-5447

Immediate Actions Required

• Restrict network access to the Linksys range extender's web management interface using firewall rules
• Disable remote management if not required, limiting access to local network only
• Change default credentials immediately and use strong, unique passwords
• Segment the network to isolate IoT and network infrastructure devices from critical systems
• Monitor affected devices for signs of compromise until patches become available

Patch Information

At the time of disclosure, Linksys had not responded to the vulnerability report, and no official patch is available. Organizations should monitor the Linksys Official Site for firmware updates addressing this vulnerability. Consider replacing affected devices with models that receive regular security updates if patches are not released in a timely manner.

Workarounds

• Implement network-level access controls to restrict who can access the device's web interface
• Use VPN or other secure access methods for remote administration rather than exposing the management interface
• Deploy an intrusion prevention system (IPS) with signatures to block command injection attempts
• Consider isolating affected devices on a separate VLAN with strict egress filtering
• If the device is not critical, consider temporarily disabling it until a patch is available

Network administrators should implement strict access controls at the network perimeter:

# Example iptables rules to restrict access to device management interface
# Replace 192.168.1.100 with your Linksys device IP
# Replace 10.0.0.0/24 with your trusted management network

# Block all external access to the device's web interface
iptables -A FORWARD -d 192.168.1.100 -p tcp --dport 80 -j DROP
iptables -A FORWARD -d 192.168.1.100 -p tcp --dport 443 -j DROP

# Allow only trusted management network
iptables -I FORWARD -s 10.0.0.0/24 -d 192.168.1.100 -p tcp --dport 80 -j ACCEPT