CVE-2026-30701: WiFi Extender WDR201A Info Disclosure

CVE-2026-30701 Overview

CVE-2026-30701 is a hardcoded credential disclosure vulnerability affecting the WiFi Extender WDR201A (HW V2.1, FW LFMZX28040922V1.02). The device's web interface contains hardcoded credential disclosure mechanisms implemented through Server Side Include (SSI) directives within multiple server-side web pages, including login.shtml and settings.shtml. These pages embed server-side execution directives that dynamically retrieve and expose the web administration password from non-volatile memory at runtime.

Critical Impact

Attackers with network access to the device can extract administrative credentials directly from the web interface, enabling complete device compromise and potential network pivot attacks.

Affected Products

• WiFi Extender WDR201A (Hardware Version 2.1)
• Firmware Version LFMZX28040922V1.02

Discovery Timeline

• 2026-03-18 - CVE CVE-2026-30701 published to NVD
• 2026-03-19 - Last updated in NVD database

Technical Details for CVE-2026-30701

Vulnerability Analysis

This vulnerability represents a fundamental design flaw in the WiFi Extender WDR201A's web administration interface. The device implements Server Side Includes (SSI) technology to dynamically generate content for its web pages. However, the implementation exposes sensitive credential information by embedding SSI directives that read the administrator password directly from non-volatile memory (NVRAM) and include it in the HTML response.

The affected pages, login.shtml and settings.shtml, contain SSI directives that execute at runtime on the embedded web server. When these pages are requested, the server processes the SSI commands, retrieves the stored administrative password, and includes it in the response sent to the client. This means that any user who can access these pages—whether authenticated or not—may be able to view the administrative credentials.

This type of vulnerability is particularly concerning in IoT devices like WiFi extenders because they often operate with minimal security controls and are frequently deployed in environments where they may be accessible to untrusted users on the local network segment.

Root Cause

The root cause of this vulnerability is the improper implementation of Server Side Include (SSI) functionality within the device's embedded web server. The developers embedded SSI directives that directly reference and expose the administrative password stored in non-volatile memory. This represents a failure to apply secure coding practices for credential handling, where sensitive data should never be directly embedded in client-facing pages regardless of the server-side technology used.

The vulnerability stems from a lack of separation between credential storage/retrieval mechanisms and the presentation layer of the web interface. Proper implementation would require authentication and authorization checks before any credential-related data is processed or displayed.

Attack Vector

The attack exploits the web interface's improper handling of SSI directives. An attacker with network access to the WiFi Extender can request the affected pages (login.shtml or settings.shtml) and examine the response to extract the administrative password.

The exploitation process involves accessing the vulnerable pages through a standard HTTP request. When the embedded web server processes these pages, the SSI directives execute and retrieve the administrative credentials from NVRAM, which are then included in the HTTP response. The attacker can examine the HTML source or the raw HTTP response to identify and extract the exposed credentials. For detailed technical analysis of this vulnerability, see the GitHub Vulnerability Disclosure.

Detection Methods for CVE-2026-30701

Indicators of Compromise

• Unusual or repeated HTTP requests to login.shtml or settings.shtml from unexpected IP addresses
• Network traffic analysis showing credential-like strings in HTTP responses from the device
• Configuration changes or unauthorized administrative access to the WiFi extender
• Evidence of network reconnaissance targeting IoT devices on the local network segment

Detection Strategies

• Implement network monitoring to detect HTTP traffic to the WiFi Extender's web interface, particularly requests for .shtml files
• Deploy intrusion detection rules to identify patterns consistent with credential harvesting from embedded device web interfaces
• Monitor for unauthorized configuration changes on network infrastructure devices including WiFi extenders
• Use network segmentation monitoring to detect lateral movement attempts following potential credential compromise

Monitoring Recommendations

• Isolate IoT devices like WiFi extenders on dedicated network segments with limited access
• Enable logging on network firewalls and switches to track access to embedded device management interfaces
• Consider implementing a network access control solution to restrict which devices can communicate with IoT management interfaces
• Regularly audit device configurations to detect unauthorized changes that may indicate compromise

How to Mitigate CVE-2026-30701

Immediate Actions Required

• Restrict network access to the WiFi Extender's web management interface using firewall rules or network segmentation
• Disable remote management if not required and limit access to the management interface to trusted administrative workstations only
• Monitor the vendor for firmware updates that address this vulnerability
• Consider replacing the affected device with a product from a vendor with better security practices if no patch is forthcoming

Patch Information

At the time of publication, no vendor patch has been confirmed for this vulnerability. Users should monitor the vendor's support channels and the GitHub Vulnerability Disclosure for updates on remediation options.

Workarounds

• Implement strict network ACLs to limit which hosts can access the device's web interface on port 80/443
• Place the WiFi Extender on an isolated VLAN with no direct access from untrusted network segments
• If the device supports it, disable the web management interface entirely and manage via other means if available
• Consider deploying a network-based web application firewall to filter requests to the management interface

# Example: Firewall rule to restrict access to WiFi Extender management interface
# Replace 192.168.1.100 with your WiFi Extender's IP address
# Replace 192.168.1.50 with your trusted admin workstation IP

# iptables example (Linux firewall/router)
iptables -A FORWARD -d 192.168.1.100 -p tcp --dport 80 -s 192.168.1.50 -j ACCEPT
iptables -A FORWARD -d 192.168.1.100 -p tcp --dport 80 -j DROP