CVE-2026-4164: Wavlink WL-WN578W2 RCE Vulnerability

CVE-2026-4164 Overview

A command injection vulnerability has been identified in the Wavlink WL-WN578W2 wireless router firmware version 221110. The vulnerability exists in the Delete_Mac_list, SetName, and GuestWifi functions within the /cgi-bin/wireless.cgi POST request handler component. Attackers can exploit this flaw by manipulating input parameters to inject and execute arbitrary system commands on the affected device.

Critical Impact

Remote attackers can achieve full device compromise through command injection, potentially gaining complete control over the router without authentication, enabling network traffic interception, lateral movement, and persistent access to the target network.

Affected Products

• Wavlink WL-WN578W2 Firmware version 221110
• Wavlink WL-WN578W2 wireless routers with vulnerable CGI handler

Discovery Timeline

• 2026-03-16 - CVE-2026-4164 published to NVD
• 2026-03-16 - Last updated in NVD database

Technical Details for CVE-2026-4164

Vulnerability Analysis

This command injection vulnerability (CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component) affects the wireless configuration interface of the Wavlink WL-WN578W2 router. The affected CGI handler fails to properly sanitize user-supplied input in the Delete_Mac_list, SetName, and GuestWifi functions before passing the data to system shell commands.

When processing POST requests to /cgi-bin/wireless.cgi, the router's firmware does not adequately validate or escape special characters in user input. This allows an attacker to append shell metacharacters and arbitrary commands that are subsequently executed with the privileges of the web server process, typically running as root on embedded devices.

The vulnerability is remotely exploitable and requires no authentication, making it particularly dangerous for devices exposed to the internet or accessible from compromised internal networks.

Root Cause

The root cause lies in insufficient input validation within the CGI request handler. The Delete_Mac_list, SetName, and GuestWifi functions directly incorporate user-supplied parameters into system commands without proper sanitization. This failure to neutralize special elements before command execution creates a classic OS command injection scenario where shell metacharacters such as semicolons, pipes, or backticks can be used to break out of the intended command context and execute attacker-controlled commands.

Attack Vector

The attack can be conducted remotely over the network by sending specially crafted HTTP POST requests to the /cgi-bin/wireless.cgi endpoint. An attacker can inject malicious commands by including shell metacharacters in the parameters processed by the vulnerable functions.

The attack flow typically involves:

1. Identifying a target Wavlink WL-WN578W2 device on the network
2. Crafting a malicious POST request containing command injection payloads in affected parameters
3. Sending the request to the /cgi-bin/wireless.cgi endpoint
4. The injected commands execute with device-level privileges, potentially granting full system access

Technical details regarding the specific exploitation methodology can be found in the GitHub vulnerability documentation for vul_1 and vul_2, as well as the VulDB entry #351071.

Detection Methods for CVE-2026-4164

Indicators of Compromise

• Unusual HTTP POST requests targeting /cgi-bin/wireless.cgi containing shell metacharacters (;, |, `, $())
• Unexpected outbound network connections from the router to external IP addresses
• Anomalous process executions on the device, particularly shells spawned by the web server process
• Modified configuration files or unauthorized firmware changes on the device
• Network traffic anomalies indicating potential command-and-control communication

Detection Strategies

• Monitor and log all HTTP POST requests to /cgi-bin/wireless.cgi endpoints on Wavlink devices
• Deploy network intrusion detection rules to identify command injection patterns in CGI parameters
• Implement web application firewall (WAF) rules to block requests containing shell metacharacters in wireless configuration endpoints
• Use SentinelOne Singularity™ for network traffic analysis to detect exploitation attempts and post-compromise behavior

Monitoring Recommendations

• Enable comprehensive logging on network perimeter devices monitoring router management interfaces
• Configure alerting for any external access attempts to router administration CGI endpoints
• Periodically audit firmware versions on all Wavlink WL-WN578W2 devices in the network
• Monitor for indicators of router compromise including DNS hijacking or traffic redirection

How to Mitigate CVE-2026-4164

Immediate Actions Required

• Restrict network access to the router's administration interface to trusted management networks only
• Disable remote management features if not required
• Place affected Wavlink WL-WN578W2 routers behind a firewall that blocks external access to CGI endpoints
• Monitor devices for signs of compromise until patches can be applied
• Consider replacing affected devices if firmware updates are not available

Patch Information

Wavlink has released updated firmware to address this vulnerability. The patched firmware is available for download from the Wavlink firmware download page. Organizations should prioritize updating affected devices to the latest available firmware version.

Before applying the update, ensure you have a backup of the current device configuration. After updating, verify the firmware version and reset any default credentials.

Workarounds

• Implement network segmentation to isolate affected routers from critical network segments
• Use firewall rules to block access to /cgi-bin/wireless.cgi from untrusted networks
• Disable the web management interface and use serial console for administration if possible
• Deploy an upstream web application firewall to filter malicious POST requests targeting vulnerable endpoints
• Monitor network traffic for exploitation attempts while awaiting firmware updates

# Example iptables rule to restrict CGI access (apply on upstream firewall)
iptables -A FORWARD -d <ROUTER_IP> -p tcp --dport 80 -m string --string "/cgi-bin/wireless.cgi" --algo bm -j DROP
iptables -A FORWARD -d <ROUTER_IP> -p tcp --dport 443 -m string --string "/cgi-bin/wireless.cgi" --algo bm -j DROP