CVE-2026-26795: GL-iNet GL-AR300M16 RCE Vulnerability

CVE-2026-26795 Overview

CVE-2026-26795 is a command injection vulnerability discovered in the GL-iNet GL-AR300M16 router firmware version 4.3.11. The flaw exists within the M.get_system_log function, where the module parameter fails to properly sanitize user-supplied input before passing it to system commands. This vulnerability allows attackers to execute arbitrary commands on the affected device via crafted input.

Critical Impact

Attackers can achieve remote command execution on vulnerable GL-iNet GL-AR300M16 routers, potentially leading to complete device compromise, network pivoting, and persistent backdoor installation.

Affected Products

• GL-iNet GL-AR300M16 firmware version 4.3.11
• Potentially other GL-iNet router models with similar firmware architecture

Discovery Timeline

• 2026-03-12 - CVE-2026-26795 published to NVD
• 2026-03-12 - Last updated in NVD database

Technical Details for CVE-2026-26795

Vulnerability Analysis

This command injection vulnerability affects the system logging functionality of the GL-iNet GL-AR300M16 router. The M.get_system_log function accepts a module parameter that is intended to filter or specify which system logs to retrieve. However, the function fails to properly validate or sanitize this parameter before incorporating it into shell commands executed on the underlying Linux-based operating system.

The vulnerability is particularly concerning for IoT devices like routers, as these devices often operate with elevated privileges and serve as network gateways. Successful exploitation could allow an attacker to execute arbitrary commands with the same privileges as the web interface service, which typically runs as root on embedded devices.

Root Cause

The root cause of this vulnerability is improper input validation in the M.get_system_log function. The module parameter is directly concatenated or interpolated into a shell command without adequate sanitization, allowing shell metacharacters and command separators to be interpreted by the underlying shell. This classic command injection pattern occurs when user-controlled data is passed to system command execution functions without proper escaping or validation.

Attack Vector

An attacker can exploit this vulnerability by sending a malicious request to the router's web management interface with a specially crafted module parameter value. By injecting shell metacharacters such as semicolons (;), pipes (|), or command substitution syntax (`command` or $(command)), an attacker can append arbitrary commands to be executed by the system.

The attack requires network access to the router's management interface. If the management interface is exposed to the internet or accessible from an untrusted network segment, remote exploitation is possible. On devices where the management interface is only accessible from the local network, an attacker would need local network access or could potentially chain this vulnerability with a cross-site request forgery (CSRF) attack.

Technical details and proof-of-concept information are available in the GitHub IoT Vulnerability Repository.

Detection Methods for CVE-2026-26795

Indicators of Compromise

• Unusual outbound network connections from the router to unknown IP addresses
• Unexpected processes running on the router that are not part of normal firmware operations
• Modified system configuration files or unauthorized user accounts
• Web server logs showing requests to the system log endpoint with suspicious module parameter values containing shell metacharacters

Detection Strategies

• Monitor HTTP request logs for the router's web interface, looking for requests containing shell metacharacters in parameter values
• Implement network monitoring to detect unusual traffic patterns originating from the router
• Deploy intrusion detection system (IDS) rules to identify command injection patterns in HTTP traffic destined for IoT devices
• Regularly audit router configurations for unauthorized modifications

Monitoring Recommendations

• Enable comprehensive logging on network perimeter devices to capture traffic to and from IoT devices
• Implement network segmentation to isolate IoT devices and monitor cross-segment traffic
• Use security information and event management (SIEM) solutions to correlate events and detect anomalous router behavior
• Consider implementing a dedicated IoT security monitoring solution for visibility into embedded device activity

How to Mitigate CVE-2026-26795

Immediate Actions Required

• Restrict access to the router's web management interface to trusted IP addresses only
• Disable remote management if it is not required for operations
• Place the router behind a firewall or access control list that limits management access
• Monitor the GL-iNet security advisories for firmware updates addressing this vulnerability
• Consider replacing affected devices if patches are not available in a timely manner

Patch Information

At the time of publication, no official patch information is available. Device owners should monitor GL-iNet's official website and security advisories for firmware updates that address CVE-2026-26795. Apply any security patches as soon as they become available.

Workarounds

• Configure firewall rules to restrict access to the router's management interface to specific trusted IP addresses
• Disable the web management interface if it is not required and manage the device through console access only
• Implement network segmentation to prevent untrusted devices from accessing the router's management interface
• Use a VPN for remote management access instead of exposing the web interface directly

# Example iptables rules to restrict management access (apply on upstream firewall)
# Allow management access only from trusted admin network
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP